Stem Cell Aggregates and Methods for Making and Using

ABSTRACT

The invention is directed to compositions of cell aggregates and methods for making and using the cell aggregates where the aggregates comprise cells that are not embryonic stem cells but can differentiate into cell types of at least two of ectodermal, undo dermal, and mesodermal embryonic germ layers, e.g., stem cells.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 61/022,121, filed Jan. 18, 2008, which is incorporated herein byreference.

FIELD OF THE INVENTION

The invention is directed to compositions of cell aggregates and methodsfor making and using the cell aggregates where the aggregates comprisecells that are not embryonic stem cells but can differentiate into celltypes of at least two of ectodermal, endodermal, and mesodermalembryonic germ layers, e.g., stem cells.

BACKGROUND OF THE INVENTION Stem Cells

Stem cells are characterized in that they are capable of self renewal(cell division without differentiation) and also of producing progenythat are more differentiated. The quintessential stem cell historicallyis the embryonic stem (ES) cell. The ES cell has unlimited self-renewal.ES cells are derived from the inner cell mass of the blastocyst orprimordial germ cells from a post-implantation embryo (embryonal germcells or EG cells). ES and EG cells have been derived, among others,from mouse, non-human primates and humans. When introduced intoblastocysts, ES cells can contribute to all tissues. A drawback to EScell therapy is that when transplanted in post-natal animals, ES and EGcells generate teratomas.

ES (and EG) cells can be identified by positive staining with antibodiesto SSEA1 (mouse) and SSEA4 (human). At the molecular level, ES and EGcells express a number of transcription factors specific for theseundifferentiated cells. These include oct3/4 and rex-1. Also found arethe LIF-R (in mouse) and the transcription factors sox-2 and rox-1.Rox-1 and sox-2 are also expressed in non-ES cells. A hallmark of EScells is telomerase enzyme activity, which provides these cells with anunlimited self-renewal potential in vitro. See, for example, U.S. Pat.Nos. 5,453,357; 5,656,479; 5,670,372; 5,843,780; 5,874,301; 5,914,268;6,110,739 6,190,910; 6,200,806; 6,432,711; 6,436,701, 6,500,668;6,703,279; 6,875,607; 7,029,913; 7,112,437; 7,145,057; 7,153,684; and7,294,508, each of which is incorporated by reference for teaching EScells and methods of making them. ES cells have been grown in aggregateform. They are able to form embryoid bodies when grown withoutattachment to a substrate.

Oct3/4 (oct3 in humans) is a transcription factor expressed in thepregastrulation embryo, early cleavage stage embryo, cells of the innercell mass of the blastocyst, and in embryonic carcinoma (EC) cells(Nichols et al., Cell 95:379-91 (1998)), and is down-regulated whencells are induced to differentiate. Expression of oct3/4 plays animportant role in determining early steps in embryogenesis anddifferentiation. Oct3/4, in combination with rox-1, causestranscriptional activation of the Zn-finger protein rex-1, also requiredfor maintaining undifferentiated ES cells (Rosfjord and Rizzino, BiochemBiophys Res Commun 203:1795-802 (1997); Ben-Shushan et al., Mol CellBiol 18:1866-78 (1998)). In addition, sox-2, expressed in ESC/EC, butalso in other more differentiated cells, is needed together with oct3/4to retain the undifferentiated state (Uwanogho et al., Mech Dev 49:23-36(1995)). Maintenance of murine ES cells and primordial germ cellsrequires the presence of LIF. The oct3/4 gene is transcribed into atleast two splice variants in humans, oct3A and oct3B. The oct3B splicevariant is found in many differentiated cells whereas the oct3A splicevariant (also previously designated oct3/4) is reported to be specificfor the undifferentiated ES cell. See Shimozaki et al. Development130:2505-12 (2003).

SUMMARY OF THE INVENTION

1. The invention provides a composition comprising an aggregate ofcells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

2. The invention further provides a composition comprising an aggregateof cells in cell culture, wherein said aggregate of cells comprisescells that are not embryonic stem cells, embryonic germ cells, or germcells and can differentiate into cell types of at least two of theendodermal, ectodermal and mesodermal embryonic lineages.

3. The invention further provides a pharmaceutical compositioncomprising a pharmaceutically-acceptable carrier and an aggregate ofcells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

4. The invention further provides a composition comprising cells derivedfrom an aggregate of cells, wherein said aggregate of cells comprisescells that are not embryonic stem cells, embryonic germ cells, or germcells and can differentiate into cell types of at least two of theendodermal, ectodermal and mesodermal embryonic lineages.

5. The invention further provides a composition comprising, in cellculture, cells derived from an aggregate of cells, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

6. The invention further provides a pharmaceutical compositioncomprising a pharmaceutically-acceptable carrier and cells derived froman aggregate of cells, wherein said aggregate of cells comprises cellsthat are not embryonic stem cells, embryonic germ cells, or germ cellsand can differentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

7. The invention further provides a composition comprising adifferentiated cell produced by exposing an aggregate of cells, whereinsaid aggregate of cells comprises cells that are not embryonic stemcells, embryonic germ cells, or germ cells and can differentiate intocell types of at least two of the endodermal, ectodermal and mesodermalembryonic lineages, to conditions producing said differentiated cell.

8. The invention further provides a composition comprising, in cellculture, a differentiated cell produced by exposing an aggregate ofcells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages, to conditions producingsaid differentiated cell.

9. The invention further provides a pharmaceutical compositioncomprising a pharmaceutically-acceptable carrier and a differentiatedcell, said differentiated cell produced by exposing an aggregate ofcells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and that candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages, to conditions producingsaid differentiated cell.

10. The invention further provides a composition comprising adifferentiated cell produced by exposing cells derived from an aggregateof cells to conditions producing said differentiated cell, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

11. The invention further provides a composition, comprising, in cellculture, a differentiated cell produced by exposing cells derived froman aggregate of cells to conditions producing said differentiated cell,wherein said aggregate of cells comprises cells that are not embryonicstem cells, embryonic germ cells, or germ cells and can differentiateinto cell types of at least two of the endodermal, ectodermal andmesodermal embryonic lineages.

12. The invention further provides a pharmaceutical compositioncomprising a pharmaceutically-acceptable carrier and a differentiatedcell produced by exposing cells derived from an aggregate of cells toconditions producing said differentiated cell, wherein said aggregate ofcells comprises cells that are not embryonic stem cells, embryonic germcells, or germ cells and can differentiate into cell types of at leasttwo of the endodermal, ectodermal and mesodermal embryonic lineages.

13. The invention further provides a method for making an aggregate ofcells, said method comprising exposing cells that are not embryonic stemcells, embryonic germ cells, or germ cells and can differentiate intocell types of at least two of the endodermal, ectodermal and mesodermalembryonic lineages to conditions under which said cells aggregate.

14. The invention further provides a method for making an aggregate ofcells in cell culture, said method comprising exposing cells, in cellculture, to conditions under which said cells aggregate, wherein saidcells from which the aggregate is made are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

15. The invention further provides a method for making a pharmaceuticalcomposition, said method comprising admixing apharmaceutically-acceptable carrier with an aggregate of cells, saidaggregate of cells comprising cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

16. The invention further provides a method for making cells derivedfrom an aggregate of cells, said method comprising dis-aggregating cellsin an aggregate of cells, said aggregate of cells comprising cells thatare not embryonic stem cells, embryonic germ cells, or germ cells andcan differentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

17. The invention further provides a method for making a cell culturecomposition, said method comprising introducing, into a culture medium,cells derived from an aggregate of cells, wherein said aggregate ofcells comprises cells that are not embryonic stem cells, embryonic germcells, or germ cells and can differentiate into cell types of at leasttwo of the endodermal, ectodermal, and mesodermal embryonic lineages.

18. The invention further provides a method for making a pharmaceuticalcomposition, said method comprising admixing apharmaceutically-acceptable carrier with cells derived from an aggregateof cells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal, and mesodermal embryonic lineages.

19. The invention further provides a method for making a differentiatedcell, said method comprising exposing an aggregate of cells, whereinsaid aggregate of cells comprises cells that are not embryonic stemcells, embryonic germ cells, or germ cells and can differentiate intocell types of at least two of the endodermal, ectodermal, and mesodermalembryonic lineages, to conditions producing said differentiated cell.

20. The invention further provides a method for making a differentiatedcell, said method comprising exposing an aggregate of cells, in cellculture, to conditions producing said differentiated cell, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

21. The invention further provides a method for making a cell culturecomposition, said method comprising combining a differentiated cell witha cell culture medium, said differentiated cell having been produced byexposing an aggregate of cells to conditions producing saiddifferentiated cell, wherein said aggregate of cells comprises cellsthat are not embryonic stem cells, embryonic germ cells, or germ cellsand can differentiate into cell types of at least two of the endodermal,ectodermal, and mesodermal embryonic lineages.

22. The invention further provides a method for making a pharmaceuticalcomposition, said method comprising admixing apharmaceutically-acceptable carrier with a differentiated cell producedby exposing an aggregate of cells to conditions producing saiddifferentiated cell, wherein said aggregate of cells comprises cellsthat are not embryonic stem cells, embryonic germ cells, or germ cellsand can differentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

23. The invention further provides a method for making a differentiatedcell, said method comprising exposing a cell derived from an aggregateof cells to conditions producing said differentiated cell, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal, and mesodermalembryonic lineages.

24. The invention further provides a method for making a differentiatedcell, said method comprising exposing, in cell culture, cells derivedfrom an aggregate of cells to conditions producing said differentiatedcell, wherein said aggregate of cells comprises cells are not embryonicstem cells, embryonic germ cells, or germ cells and can differentiateinto cell types of at least two of the endodermal, ectodermal andmesodermal embryonic lineages.

25. The invention further provides a method for making a cell culturecomposition, said method comprising combining a differentiated cell witha cell culture medium, said differentiated cell having been produced byexposing cells derived from an aggregate of cells to conditionsproducing said differentiated cell, wherein said aggregate of cellscomprises cells that are not embryonic stem cells, embryonic germ cells,or germ cells and can differentiate into cell types of at least two ofthe endodermal, ectodermal, and mesodermal embryonic lineages.

26. The invention further provides a method for making a pharmaceuticalcomposition, said method comprising admixing a differentiated cell witha pharmaceutically-acceptable carrier, said cell having been produced byexposing cells derived from an aggregate of cells to conditionseffective to achieve the differentiated cell phenotype, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal, and mesodermalembryonic lineages.

27. The invention further provides a method comprising administering toa subject an aggregate of cells, wherein said aggregate of cellscomprises cells that are not embryonic stem cells, embryonic germ cells,or germ cells and can differentiate into cell types of at least two ofthe endodermal, ectodermal and mesodermal embryonic lineages.

28. The invention further provides a method comprising administering toa subject a pharmaceutical composition comprising apharmaceutically-acceptable carrier and an aggregate of cells, whereinsaid aggregate of cells comprises cells that are not embryonic stemcells, embryonic germ cells, or germ cells and can differentiate intocell types of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

29. The invention further provides a method comprising administering toa subject cells derived from an aggregate of cells, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

30. The invention further provides a method comprising administering toa subject a pharmaceutical composition comprising apharmaceutically-acceptable carrier and cells derived from an aggregateof cells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal, and mesodermal embryonic lineages.

31. The invention further provides a method comprising administering toa subject a differentiated cell produced by exposing an aggregate ofcells to conditions producing said differentiated cell, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

32. The invention further provides a method comprising administering toa subject a pharmaceutical composition comprising apharmaceutically-acceptable carrier and a differentiated cell, thedifferentiated cell produced by exposing an aggregate of cells toconditions producing said differentiated cell, wherein said aggregate ofcells comprises cells that are not embryonic stem cells, embryonic germcells, or germ cells and can differentiate into cell types of at leasttwo of the endodermal, ectodermal, and mesodermal embryonic lineages.

33. The invention further provides a method comprising administering toa subject a differentiated cell produced by exposing cells derived froman aggregate of cells to conditions producing said differentiated cell,wherein said aggregate of cells comprises cells that are not embryonicstem cells, embryonic germ cells, or germ cells and that candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

34. The invention further provides a method comprising administering toa subject a pharmaceutical composition comprising apharmaceutically-acceptable carrier and a differentiated cell, thedifferentiated cell produced by exposing cells derived from an aggregateof cells to conditions producing said differentiated cell, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal, and mesodermalembryonic lineages.

35. The invention further provides a method of identifying an activeagent, said method comprising contacting an aggregate of cells with anagent, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages, and detecting the effectof the agent on said aggregate of cells.

36. The invention further provides a method of identifying an activeagent, said method comprising contacting an aggregate of cells with anagent in cell culture, wherein said aggregate of cells comprises cellsthat are not embryonic stem cells, embryonic germ cells, or germ cellsand can differentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages, and detecting the effectof the agent on said aggregate of cells.

37. The invention further provides a method of identifying an activeagent, said method comprising contacting cells derived from an aggregateof cells with an agent, wherein said aggregate of cells comprises cellsthat are not embryonic stem cells, embryonic germ cells, or germ cellsand can differentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages, and detecting the effectof the agent on said cells derived from said aggregate of cells.

38. The invention further provides a method of identifying an activeagent, said method comprising contacting, in cell culture, cells derivedfrom an aggregate of cells with an agent, wherein said aggregate ofcells comprises cells that are not embryonic stem cells, embryonic germcells, or germ cells and can differentiate into cell types of at leasttwo of the endodermal, ectodermal and mesodermal embryonic lineages, anddetecting the effect of the agent on said cells derived from saidaggregate of cells.

39. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of an aggregate of cells, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

40. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of a pharmaceutical compositioncomprising a pharmaceutically-acceptable carrier and an aggregate ofcells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

41. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of cells derived from an aggregate ofcells, wherein said aggregate of cells comprises cells that are notembryonic stem cells, embryonic germ cells, or germ cells and candifferentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

42. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of a pharmaceutical compositioncomprised of a pharmaceutically-acceptable carrier and cells derivedfrom an aggregate of cells, wherein said aggregate of cells comprisescells that are not embryonic stem cells, embryonic germ cells, or germcells and can differentiate into cell types of at least two of theendodermal, ectodermal and mesodermal embryonic lineages.

43. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of a differentiated cell produced byexposing an aggregate of cells to conditions producing saiddifferentiated cell, wherein said aggregate of cells comprises cellsthat are not embryonic stem cells, embryonic germ cells, or germ cellsand can differentiate into cell types of at least two of the endodermal,ectodermal and mesodermal embryonic lineages.

44. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of a pharmaceutical compositioncomprising a pharmaceutically-acceptable carrier and a differentiatedcell, said differentiated cell produced by exposing an aggregate ofcells to conditions producing said differentiated cell, wherein saidaggregate of cells comprises cells that are not embryonic stem cells,embryonic germ cells, or germ cells and can differentiate into celltypes of at least two of the endodermal, ectodermal and mesodermalembryonic lineages.

45. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of a differentiated cell produced byexposing cells derived from an aggregate of cells to conditionsproducing said differentiated cell, wherein said aggregate of cellscomprises cells that are not embryonic stem cells, embryonic germ cells,or germ cells and can differentiate into cell types of at least two ofthe endodermal, ectodermal and mesodermal embryonic lineages.

46. The invention further provides a method of treating a disorder in asubject in need of treatment, said method comprising administering atherapeutically effective amount of a pharmaceutical compositioncomprising a pharmaceutically-acceptable carrier and a differentiatedcell produced by exposing cells derived from an aggregate of cells toconditions producing said differentiated cell, wherein said aggregate ofcells comprises cells that not embryonic stem cells, embryonic germcells, or germ cells and can differentiate into cell types of at leasttwo of the endodermal, ectodermal and mesodermal embryonic lineages.

47. The invention further provides the compositions herein, whereincells in the aggregate and cells derived from the aggregate express oneor more of oct3/4, telomerase, rex-1, rox-1, nanog, GATA6 and sox-2.

48. The invention further provides the compositions herein, whereincells in the aggregate and cells derived from the aggregate candifferentiate into cell types of all three of the endodermal,ectodermal, and mesodermal embryonic lineages.

49. The invention further provides the compositions herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses one or more of endodermal,ectodermal, and mesodermal differentiation markers.

50. The invention further provides the compositions herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses endodermal and ectodermaldifferentiation markers.

51. The invention further provides the compositions herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses ectodermal and mesodermaldifferentiation markers.

52. The invention further provides the compositions herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses endodermal and mesodermaldifferentiation markers.

53. The invention further provides the compositions herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses an endodermal differentiationmarker.

54. The invention further provides the compositions herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses an ectodermal differentiationmarker.

55. The invention further provides the compositions herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses a mesodermal differentiationmarker.

56. The invention further provides the compositions herein, wherein thedifferentiated cell phenotype, produced by differentiating the aggregateor cells derived from the aggregate, is characteristic of cells selectedfrom the group consisting of hepatocytes, beta islet cells, neurons,osteoblasts, astrocytes, oligodendrocytes, cartilage, bone, muscle,connective tissue, mesangioblasts, hematopoietic stem cells,lymphocytes, reticulocytes, myeloid cells, pulmonary epithelia and skin.

57. The invention further provides the compositions herein, wherein theaggregate contains about 10 cells to about 50,000 cells or more.

58. The invention further provides the compositions herein, wherein theaggregate contains about 1000 cells to about 5000 cells.

59. The invention further provides the compositions herein, whereincells are aggregated by the hanging drop method or forced aggregationmethod.

60. The invention further provides the compositions herein, wherein thedifferentiated cell phenotype is selected from the group consisting ofosteoblast, chondrocyte, bone, adipocyte, cartilage, fibroblast, marrowstroma, skeletal muscle, smooth muscle, cardiac muscle, ocular,endothelial, epithelial, hepatic, pancreatic, hematopoietic, glial,neuronal and oligodendrocyte cell type.

61. The invention further provides the compositions herein, wherein thedifferentiated cell is definitive endoderm.

62. The invention further provides the compositions herein, wherein thedifferentiated cell is ventral foregut endoderm.

63. The invention further provides the compositions herein, wherein thedifferentiated cell is a bi-potential hepatic progenitor.

64. The invention further provides the compositions herein, wherein thedifferentiated cell is a hepatocyte-like cell.

65. The invention further provides the methods herein, wherein cells inthe aggregate or cells derived from the aggregate express one or more ofoct3/4, telomerase, rex-1, rox-1, nanog, GATA6 and sox-2.

66. The invention further provides the methods herein, wherein cells inthe aggregate or cells derived from the aggregate can differentiate intocell types of all three of the endodermal, ectodermal and mesodermalembryonic lineages.

67. The invention further provides the methods herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses one or more of endodermal,ectodermal and mesodermal differentiation markers.

68. The invention further provides the methods herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses endodermal and ectodermaldifferentiation markers.

69. The invention further provides the methods herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses ectodermal and mesodermaldifferentiation markers.

70. The invention further provides the methods herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses endodermal and mesodermaldifferentiation markers.

71. The invention further provides the methods herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses an endodermal differentiationmarker.

72. The invention further provides the methods herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses an ectodermal differentiationmarker.

73. The invention further provides the methods herein, wherein thedifferentiated cell, produced by differentiating the aggregate or cellsderived from the aggregate, expresses a mesodermal differentiationmarker.

74. The invention further provides the methods herein, wherein thedifferentiated cell phenotype is characteristic of cells selected fromthe group consisting of hepatocytes, beta islet cells, neurons,osteoblasts, astrocytes, oligodendrocytes, cartilage, bone, muscle,connective tissue, mesangioblasts, hematopoietic stem cells,lymphocytes, reticulocytes, myeloid cells, pulmonary epithelia and skin.

75. The invention further provides the methods herein, wherein theaggregate contains about 10 cells to about 50,000 cells or more.

76. The invention further provides the methods herein, wherein theaggregate contains about 1000 cells to about 5000 cells.

77. The invention further provides the methods herein, wherein cells areaggregated by the hanging drop method or forced aggregation method.

78. The invention further provides the methods herein, wherein thedisorder is a liver disease or disorder, GVHD, myocardial infarction,congestive heart failure, diabetes, hematopoietic transplant, traumaticbrain injury, spinal cord injury or stroke.

79. The invention further provides the methods herein, wherein thedisorder involves damaged tissue and the tissue is one or more ofcardiac, neuronal, ocular, cartilage, bone, skeletal muscle, smoothmuscle, bone marrow, spleen, liver, lung, brain, immune system,connective, blood vessel, pancreas, CNS, PNS and kidney tissue.

80. The invention further provides the methods herein, wherein thedifferentiated cell phenotype is selected from the group consisting ofosteoblast, chondrocyte, bone, adipocyte, cartilage, fibroblast, marrowstroma, skeletal muscle, smooth muscle, cardiac muscle, ocular,endothelial, epithelial, hepatic, pancreatic, hematopoietic, glial,neuronal and oligodendrocyte cell type.

81. The invention further provides the methods herein, wherein thedifferentiated cell is definitive endoderm.

82. The invention further provides the methods herein, wherein thedifferentiated cell is ventral foregut endoderm.

83. The invention further provides the methods herein, wherein thedifferentiated cell is a bi-potential hepatic progenitor.

84. The invention further provides the methods herein, wherein thedifferentiated cell is a hepatocyte-like cell.

In the above statements of the invention, cells derived from theaggregate can retain the differentiation capacity of the aggregatedcells.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the hanging drop method for forming aggregates from ratMAPCs in monolayer (2D) culture and subsequent differentiation. After4-5 days of aggregate formation in the hanging drop in MAPC media and 5%oxygen, cell aggregates are transferred to the ultra-low attachmentplate for differentiation in corresponding differentiation media. Theright panel illustrates the morphology of the cells in 2D monolayer,undifferentiated cell aggregates, and then differentiated cellaggregates.

FIG. 2 shows aggregates formed from rat MAPC under different mediaconditions. Under optimum MAPC media conditions, the aggregates grow upinto spherical clusters with well defined boundary. Withdrawal of LIFfrom MAPC media induces formation of aggregates with irregular boundarycorresponding to early signs of differentiation. In differentiationbasal media, the cell aggregates are much smaller due to non-optimalgrowth conditions.

FIG. 3 shows the percentage of cells expressing oct3/4 (transcriptionfactor associated with the undifferentiated status of MAPCs). Out of the76% of cells that expressed oct3/4 in 2D monolayer, 70% still retainedthe expression of oct3/4 in the MAPC aggregates when they were formed inMPAC media and 5% oxygen. Other conditions were different mediacompositions: —MAPC media without LIF, differentiation basal media, andchoice of oxygen levels −5% (hypoxic) or 21% (normoxic).

FIG. 4 shows a QRT-PCR expression profile for several differentiationmarkers in MAPC 2D and 3D cultures formed by the hanging drop method andforced aggregation method. The expression of oct3/4 and GATA6 are bothcomparable between 2D MAPCs and 3D MAPC aggregates irrespective of themethod of formation. There is little expression of early endodermmarkers HNF3b and Goosecoid (Gsc) and no expression of mature endodermmarkers like AFP, albumin, Alpha-1-Antitrypsin (AAT) and Tyrosine aminotransferase (TAT) in 3D MAPC aggregates similar to MAPCs 2D.

FIG. 5 shows low oct3/4 MAPC aggregates formed from low oct3/4 MAPCs in2D culture in MAPC medium and 5% oxygen in 7 days. Upon spontaneousdifferentiation in differentiation basal media and 21% oxygen,aggregates differentiated to cells that appeared like adipocytes andfibroblasts by morphology.

FIG. 6 shows high oct3/4 MAPC trypsinized and replated ontofibronectin-coated dishes in MAPC medium and 5% oxygen. The morphologyof cells are typical of MAPCs, they are capable of undergoing expansionillustrated by the increase in cell number with time and retain theexpression of MAPC markers oct3/4 and GATA6 at passage 1 (2D P2) andpassage 2 (2D P2) after replating at levels expressed by MAPCsaggregates they came from. There is little or no expression of earlydifferentiated markers like Goosecoid (Gsc) or Brachyury (Bry) and noexpression of more mature marker like Alpha-fetoprotein (AFP).

FIG. 7 shows spontaneous multi-lineage differentiation of MAPCaggregates in differentiation basal medium with 2% serum. The levels ofoct3/4 goes down corresponding to differentiation and increase inexpression of markers of the three germ layers are observed-Nestin, Pax6(neuroectoderm), SM22, Flk-1 (mesoderm), AFP, Albumin (endoderm).

FIG. 8 shows characterization of MAPC aggregates using QRT-PCR.

FIG. 9 shows results of differentiation using a multi-step protocol.

FIG. 10 shows morphology of aggregates after 21 days of differentiation(10×).

FIG. 11 shows directed differentiation to hepatocytes (FIG. 11A),endothelial cells (FIG. 11B), and neural precursors (FIG. 11C), startingfrom rat MAPC lines R2old and 19 maintained undifferentiated in 2D vs.3D conditions.

DETAILED DESCRIPTION OF THE INVENTION Definitions

As used herein, the terms below are defined by the following meanings.

“2D” refers to cell culture where cells grow by attaching (adhering) toa substrate. Such cells form monolayers or colonies where the cells areeach attached to a substrate (where the substrate is other than thecells themselves).

“3D” refers to cell culture where cells grow as an aggregate throughassociation of the cells with each other and not through associationwith a substrate other than the cells themselves. In the art, “3D” mayrefer to growth of cells on a scaffold or matrix. But, as used herein,3D is used as above.

In one embodiment, cells can be initially grown on a substrate wheresome cells associate with (adhere to) the substrate but further growthforms cell-cell associations (aggregation) that do not depend onassociation (adherence) of the further-grown cells with the substrate. Acellular feeder layer is also considered a substrate. So attachment ofcells to a feeder layer is also a form of adherent culture (not anaggregate) since attachment of the cells is not to each other but to thecells in the feeder layer.

“A” or “an” means one or more than one.

“Aggregate” refers to an association of cells in which the associationis caused by cell-cell interaction rather than adherence to a substrate.In 2D monolayer culture, cells are “associated” with each other but bymeans of attachment to a substrate material, such as plastic or surfacecoating. In an aggregate, two or more cells associate with each other bybiologic attachments to one another. This can be through surfaceproteins, such as extracellular matrix proteins.

“Co-administer” can include simultaneous or sequential administration oftwo or more agents.

“Comprising” means, without other limitation, including the referent,necessarily, without any qualification or exclusion on what else may beincluded. For example, “a composition comprising x and y” encompassesany composition that contains x and y, no matter what other componentsmay be present in the composition. Likewise, “a method comprising thestep of x” encompasses any method in which x is carried out, whether xis the only step in the method or it is only one of the steps, no matterhow many other steps there may be and no matter how simple or complex xis in comparison to them. “Comprised of” and similar phrases using wordsof the root “comprise” are used herein as synonyms of “comprising” andhave the same meaning.

“Cytokines” refer to cellular factors that induce or enhance cellularmovement, such as homing of stem cells, progenitor cells ordifferentiated cells such as skeletal myoblasts, cardiac myoblasts,myocytes, and the like. Cytokines may also stimulate such cells todivide.

“Definitive endodermal phenotype” is a particular phenotype of cellsthat no longer express oct3/4, do not express the primitive endodermgene Sox7, do not express the mesodermal gene Flkl, but do expressSox17, Foxa2, E-cadherin, CXCR4, and PDGF-Ra.

“Differentiation factor” refers to a cellular or chemical factor,preferably growth factor or angiogenic factor, that acts on stem orprogenitor cells to form more highly differentiated progeny.

“Dispersion” refers to cells derived from the aggregates and whichretain the function of the cells in aggregate form in that they canstill differentiate into cell types of more than one embryonic germlayer.

An “effective amount” generally means an amount which provides thedesired local or systemic effect, such as enhanced performance. Forexample, an effective dose is an amount sufficient to affect abeneficial or desired clinical result. Said dose could be administeredin one or more administrations and could include any preselected amountof cells. The precise determination of what would be considered aneffective dose may be based on factors individual to each subject,including their size, age, injury and/or disease or injury being treatedand amount of time since the injury occurred or the disease began. Oneskilled in the art, specifically a physician, would be able to determinethe number of cells that would constitute an effective dose.

“Effective amount” generally means an amount which provides the desiredlocal or systemic effect. For example, an effective amount is an amountsufficient to effectuate a beneficial or desired clinical result. Theeffective amounts can be provided all at once in a single administrationor in fractional amounts that provide the effective amount in severaladministrations. The precise determination of what would be consideredan effective amount may be based on factors individual to each subject,including their size, age, injury, and/or disease or injury beingtreated, and amount of time since the injury occurred or the diseasebegan. One skilled in the art will be able to determine the effectiveamount for a given subject based on these considerations which areroutine in the art. As used herein, “effective dose” means the same as“effective amount.”

“EC cells” were discovered from analysis of a type of cancer called ateratocarcinoma. In 1964, researchers noted that a single cell interatocarcinomas could be isolated and remain undifferentiated inculture. This type of stem cell became known as an embryonic carcinomacell (EC cell).

“Embryonic stem cells” are stem cells derived from the inner cell massof an early stage embryo known as a blastocyst. They are able todifferentiate into all derivatives of the three primary germ layers:ectoderm, endoderm, and mesoderm. These include each of the more than220 cell types in the adult body. The ES cells can become any tissue inthe body, excluding placenta.

“Expansion” refers to the propagation of a cell without differentiation.

“Hepatic differentiation factors” are chemical or biological factorsthat induce differentiation of stem and progenitor cells into moredifferentiated cells of the hepatic lineage. Hepatic differentiationfactors include, but are not limited to, Wnt3a, ActivinA, bFGF, BMP4,aFGF, FGF4, FGF8b, HGF and Follistatin. The initial cell may expressoct3/4.

“Hepatoblast phenotype” is a particular phenotype of cells thatco-express albumin, alpha fetoprotein and keratin 19, and express, onthe cell membrane, c-Met, EPCAM, and Dlk1 (Tanimizu et al., J Cell Sci116:1775-1786 (2003)).

“Hepatocyte phenotype” is a particular phenotype of cells that expressalbumin and keratin 18 but not alpha fetoprotein and keratin 19; inaddition, hepatocytes may express one or more of TAT, MRP2, G6P, GLYS2,PEPCK, A1AT, BSEP, CX-32, NTCP, CYP7A1 (rat) and CYP3A4 (human).

Use of the term “includes” is not intended to be limiting. For example,stating that stem cells “include” IPS cells does not mean that otherstem cells are excluded.

“Induced pluripotent stem cells (IPSC or IPS cells)” are somatic cellsthat have been reprogrammed. for example, by introducing exogenous genesthat confer on the somatic cell a less differentiated phenotype. Thesecells can then be induced to differentiate into more differentiatedprogeny. IPS cells have been derived using modifications of an approachoriginally discovered in 2006 (Yamanaka et al., Cell Stem Cell 1:39-49(2007)). For example, in one instance, to create IPS cells, scientistsstarted with skin cells that were then modified by a standard laboratorytechnique using retroviruses to insert genes into the cellular DNA. Inone instance, the inserted genes were Oct4, Sox2, Lif4, and c-myc, knownto act together as natural regulators to keep cells in an embryonic stemcell-like state. These cells have been described in the literature. See,for example, Wernig et al., PNAS, 105:5856-5861 (2008); Jaenisch et al.,Cell 132:567-582 (2008); Hanna et al., Cell 133:250-264 (2008); andBrambrink et al., Cell Stem Cell 2:151-159 (2008). These references areincorporated by reference for teaching IPSCs and methods for producingthem. It is also possible that such cells can be created by specificculture conditions (exposure to specific agents).

The term “isolated” refers to a cell that is not associated with one ormore cells or one or more cellular components that are associated withthe cell in vivo. An “enriched population” means a relative increase innumbers of a desired cell relative to one or more other cell types invivo or in primary culture.

However, as used herein, the term “isolated” does not indicate thepresence of only a specific desired cell, such as a stem or progenitorcell. Rather, the term “isolated” indicates that the cells are removedfrom their natural tissue environment and are present at a higherconcentration as compared to the normal tissue environment. Accordingly,an “isolated” cell population may further include cell types in additionto stem cells and may include additional tissue components. This alsocan be expressed in terms of cell doublings. For example, a cell mayundergo 10, 20, 30, 40 or more doublings in vitro or ex vivo so that itis enriched compared to its original numbers in vivo or in its originaltissue environment (e.g., bone marrow, peripheral blood, umbilical cordblood, adipose tissue, etc.)

“Liver-committed endodermal phenotype” is a particular phenotype ofcells that are EPCAM positive and Dlk1 Negative (Tanimizu et al., J CellSci 116:1775-1786 (2003)).

“MAPC” is an acronym for “multipotent adult progenitor cell”. It refersto a non-embryonic stem cell that can give rise to cell types of allthree germ layers (i.e., endoderm, mesoderm and ectoderm) upondifferentiation. Like embryonic stem cells, human MAPCs can express oneor more of telomerase, oct3/4 (i.e., oct3A), rex-1, rox-1, sox-2,SSEA-4, and may express nanog. The term “adult” in MAPC isnon-restrictive. It refers to a non-embryonic somatic cell. MAPCs arereported to express high levels of telomerase (Jiang et al., Nature418:41 (2002); Exp Hematol 30:896 (2002)) (incorporated by reference forteaching telomerase expression). MAPCs derived from human, mouse, rat orother mammals appear to be the only normal, non-malignant, somatic cell(i.e., non-germ cell) known to date to express very high levels oftelomerase even in late passage cells. The telomeres are extended inMAPCs. MAPCs are karyotypically normal.

“Multipotent,” with respect to the term in “MAPC,” refers to the abilityto give rise to cell lineages of more than one primitive germ layer(i.e., endoderm, mesoderm and ectoderm) upon differentiation, such asall three. This term is not used consistently in the literature.

“Primitive endodermal phenotype” is a particular phenotype of cells thatmay express sox7, sox17, gata4, gata6, Cited1, Tcf2, LamA1, Dab2, LamA1,LamA4, Lamc1, Co14a1, and Nidogen2 (this is a phenotype of mouse and ratMAPC, XEN cells from J. Rossant and Sox7 expressing ESC from J. Rossant.See also Ulloa-Montoya et al., Genome Biol 8:R163 (2007); Se'guin etal., Cell Stem Cell 3:182-195 (2008); and Kunath et al., Development132:1649-1661 (2005)).

“Primordial embryonic germ cells” (PG or EG cells) can be cultured andstimulated to produce many less differentiated cell types.

“Progenitor cells” are cells produced during differentiation of a stemcell that have some, but not all, of the characteristics of theirterminally differentiated progeny. Defined progenitor cells, such as“cardiac progenitor cells,” are committed to a lineage, but not to aspecific or terminally differentiated cell type. The term “progenitor”as used in the acronym “MAPC” does not limit these cells to a particularlineage.

“Self-renewal” refers to the ability to produce replicate daughter stemcells having the same differentiation potential as the parental cells. Asimilar term used in this context is “proliferation.”

“Stem cell” means a cell that can undergo self-renewal (i.e., progenywith the same differentiation potential) and also produce progeny cellsthat are more restricted in differentiation potential. Within thecontext of the invention, a stem cell would also encompass a moredifferentiated cell that has dedifferentiated, for example, by nucleartransfer, by fusions with a more primitive stem cell, by introduction ofspecific transcription factors, or by culture under specific conditions.See, for example, Wilmut et al., Nature 385:810-813 (1997); Ying et al.,Nature 416:545-548 (2002); Guan et al., Nature 440:1199-1203 (2006);Takahashi et al., Cell 126:663-676 (2006); Okita et al., Nature448:313-317 (2007); and Takahashi et al., Cell 131:861-872 (2007).

Dedifferentiation may also be caused by the administration of certaincompounds or exposure to a physical environment in vitro or in vivo thatwould cause the dedifferentiation. Stem cells also may be derived fromabnormal tissue, such as a teratocarcinoma and some other sources, suchas embryoid bodies (although these can be considered embryonic stemcells in that they are derived from embryonic tissue, although notdirectly from the inner cell mass).

A “subject” is a vertebrate, preferably a mammal, more preferably ahuman. Mammals include, but are not limited to, humans, farm animals,sport animals, and pets. Subjects in need of treatment by methods of thepresent invention include those suffering from a loss of function as aresult of physical or disease-related damage.

The term “therapeutically effective amount” refers to the amountdetermined to produce any therapeutic response in a mammal. For example,effective amounts of the therapeutic cells or cell-associated agents mayprolong the survivability of the patient, and/or inhibit overt clinicalsymptoms. Treatments that are therapeutically effective within themeaning of the term as used herein, include treatments that improve asubject's quality of life even if they do not improve the diseaseoutcome per se. Such therapeutically effective amounts are ascertainedby one of ordinary skill in the art through routine application tosubject populations such as in clinical and pre-clinical trials. Thus,to “treat” means to deliver such an amount.

“Treat,” “treating” or “treatment” are used broadly in relation to theinvention and each such term encompasses, among others, preventing,ameliorating, inhibiting, or curing a deficiency, dysfunction, disease,or other deleterious process, including those that interfere with and/orresult from a therapy.

The inventors have discovered that non-embryonic stem cells can be grownas aggregates and the aggregates comprise cells that retain theundifferentiated phenotype of the non-embryonic stem cells. Therefore,the aggregates are capable of producing progeny with a moredifferentiated phenotype. The ability to form aggregates can be usefulfor large scale cell production.

Stem cells that are useful for the invention may include cells that arenot transformed or tumorigenic. They may have a normal karyotype. Forexample, some, such as MAPC, are known not to form teratomas in vivo andto have a normal karyotype in culture.

The aggregate can be formed by using any method for non-adherent growth,such as, any of the known methods in the art. These include, but are notlimited to, the hanging drop method (Kurosawa and Hopfl, cited below),the forced aggregation method (centrifugation) (Ng, cited below),methods wherein the cells are cultured on non-adherent plastic,suspension culture (static or stirred), bioreactor expansion platforms,and non-attachment or special coating e.g., temperature-sensitivepolymer-based plates, microcontact printing of wells to control size ofcolonies, and microfluidic devices.

Many different basal media are known in the art. Such media may be usedwith or without serum (or at varying serum concentrations, e.g.,0.5%-20% or more). When serum is absent or reduced, the person ofordinary skill would know to use growth factors to complement the basalmedium, including, but not limited to, EGF and/or PDGF. Oxygenconcentrations may be reduced from atmospheric to ranges of 1-5, 5-10,10-15, 15-20% and numbers between.

The stem cells that form the aggregates can be derived from varioustissues, such as bone marrow, placenta, peripheral blood, umbilical cordblood and tissue, skin, and fat. Cells designated “MAPC” in theliterature are exemplified in this application. But the inventionfurther contemplates any non-embryonic stem cell that forms cell typesof more than one embryonic germ layer. See, for example, U.S. Pat. No.7,311,905; 2003/0059414; 2002/0164794, all incorporated by reference forteaching these cells and methods for making them.

In addition, less differentiated stem cells may be derived by variousmanipulations, such as, by transfecting and expressing certain genes indifferentiated cells to genetically reprogram the undifferentiatedstate, nuclear transfer of somatic cells into an environment thatcreates gene expression corresponding to a less differentiated phenotypethan was present in the somatic cell, growth in media and cultureconditions sufficient to maintain pluripotency (for example, “MAPCmedia” and expansion protocols), nuclear reprogramming by fusion ofsomatic cells with embryonic stem cells, culture-inducedreprogramming-cell explantation, and treatment of somatic nuclei withcell extract from oocytes or pluripotent cells (Hochedlinger andJaenisch, Nature 441: 1061-1067 (2006)).

The invention pertains to stem cells from any species and, particularly,mammalian species and, more particularly, to humans. Within a species,uses (e.g., administration of cells to a subject) can be of allogeneiccells. Across species, uses can be of xenogeneic cells. In a subject,cells can be autologous.

An aggregate, with respect to the invention, is defined as at least tencells. But ranges include aggregates that are not so large that theinner cells become necrotic. This can include aggregates of 100-300μ andnumbers in between, such as 150-250μ. The skilled person would recognizeany useful number in that range. A useful number of aggregates would begreater than 50 for clinical applications. Cell numbers are variable andrange from hundreds to ten of thousands or greater, e.g., 100-1000(about 200, 300, 400, 500, 600, 700, 800, 900 cells), 1000-10,000,(about 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000 cells),10,000-50,000 (about 20,000; 30,000; 40,000 cells) or more, etc.

The examples provided in this application utilize a cell that has beendesignated multipotent adult progenitor cell (“MAPC”). But the inventionpertains to any and all stem cells that are not embryonic cells but candifferentiate into all types of more than one germ layer (e.g., two orthree).

Another parameter in forming aggregates is the purity of the isolatedstem cell population used to form aggregates. Accordingly, in thepresent invention, aggregates may be formed of a desired stem cell thatis present in a population containing other cells as well. Bone marrowcells, for example, comprise mixed populations of cells, which can bepurified to a degree sufficient to produce a desired effect. Thoseskilled in the art can readily determine the percentage of a desiredstem cell in a population using various well-known methods, such asfluorescence activated cell sorting (FACS). Purity of a given stem cellcan also be determined according to the gene expression profile within apopulation.

Ranges of purity in populations comprising a given stem cell are about50-55%, 55-60%, and 65-70%. Other ranges include purity of about 70-75%,75-80%, 80-85%. Still other ranges include purity of about 85-90%,90-95%, and 95-100%. However, populations with lower purity can also beuseful, such as about 25-30%, 30-35%, 35-40%, 40-45% and 45-50%.

In the aggregates, the non-embryonic cells, such as MAPC, may besubstantially homogeneous or be found in less than substantiallyhomogeneous form. Purity, therefore, in the aggregate can vary as above.Furthermore, other cell types can be mixed in when forming theaggregates.

In methods in which the aggregate is subjected to differentiationconditions to produce some of the differentiated cell types discussed inthis application, many, if not most of those conditions are available tothose of ordinary skill in the art. See for example, Mays et al., ExpertOpinion Biol Ther 2:173-184 (2007) and links therein to differentiationprotocols; hepatocytes (J Clin Invest 109:1291-302; hematopoietic (J ExpMed 204:129-39), smooth muscle (J Clin Invest 116:3139-3149 (2006)).These differentiation conditions are incorporated herein by reference.Many differentiation conditions are in U.S. Pat. No. 7,015,037 and Mayset al. (above), incorporated by reference for these protocols.

One protocol for forming the aggregates is using DMEM-low glucose, MCDB,2% Fetal Calf Serum, PDGF-BB, EGF, LIF, BSA,insulin-selenium-transferrin (ITS), linoleic acid and lipid mixture and5% Oxygen. It may be preferable to use conditions that enhanceexpression of oct3/4 transcription factor, for example, at the levelsexpressed in MAPCs in 2D (adherent) cultures.

Aggregation Methods

There are at least two methods to form the aggregates: (a) hanging drop(surface tension based method); and (b) forced aggregation (physicallycentrifuging cells at 1500 rpm, 4 minutes onto the bottom of 96 wellUltra-low attachment U bottom plate (Corning). Although both methods areusable to form aggregates, the hanging drop method is morecost-effective to produce large number of aggregates. Other ways includestirred suspension or growth in a non-attachment plate/flask. Otherpotential methods of forming controlled-size aggregates would be methodssuch as microcontact printing.

These methods are illustrated below in the following citations, whichare hereby incorporated by reference for teaching various non-adherentcell culture methods.

-   Dang et al., “Efficiency of embryoid body formation and    hematopoietic development from embryonic stem cells in different    culture systems” Biotechnology and Bioengineering 78: 442-453    (2002).-   Konno et al., “Formation of embryoid bodies by mouse embryonic stem    cells on plastic surfaces” Journal of Bioscience and Bioengineering    100:88-93 (2005).-   Ng et al., Forced aggregation of defined numbers of human embryonic    stem cells into embryoid bodies fosters robust, reproducible    hematopoietic differentiation. Commentary” Blood    106:1601-1603 (2005) [Forced aggregation method].-   Kurosawa et al., “A simple method for forming embryoid body from    mouse embryonic stem cells” Journal of Bioscience and Bioengineering    96: 409-411 (2003).-   Magyar et al., “Mass production of embryoid bodies in microbeads”    Annals of the New York Academy of Sciences 944: 135-143 (2001).    [Scalable production of cell aggregates as microbeads].-   Hopfl et al., “Differentiating embryonic stem cells into embryoid    bodies” Methods Mol Biol 254:79-98 (2004) [Hanging drop method].-   Cameron et al., “Improved development of human embryonic stem    cell-derived embryoid bodies by stirred vessel cultivation”    Biotechnol Bioeng 94:938-948 (2006) [Stirred-suspension culture    system].-   Wang et al., “Scalable producing embryoid bodies by rotary cell    culture system and constructing engineered cardiac tissue with    ES-derived cardiomyocytes in vitro” Biotechnol Prog    22:811-818 (2006) [Rotary suspension systems].-   Yang et al., Biomacromolecules 8, 9, 2746-2752 (2007) [Use of    temperature sensitive hydrogel].-   Torisawa et al., “Lab on a Chip” 7:770-776 (2007) [Use of    microfluidics for efficient EB size formation].

The aggregates can be formed with a starting cell number greater than100. A maximum of 4000 cells have been used to form a single aggregateover 4 days of Hanging drop/Forced aggregation method. Starting from1000 cells, the aggregates had an approximate number of 6600cells/aggregate (counted by trypan blue exclusion method) after 4 daysof hanging drop culture. Therefore, a useful starting range could be100-4000 for each aggregate with the most optimum being between400-2000.

Stem Cells

The present invention can be practiced, preferably, using stem cells ofvertebrate species, such as humans, non-human primates, domesticanimals, livestock, and other non-human mammals.

Non-Embryonic

Non-embryonic cells reported to be capable of differentiating into celltypes of more than one embryonic germ layer include, but are not limitedto, cells from umbilical cord blood (see U.S. Publication No.2002/0164794), placenta (see U.S. Publication No. 2003/0181269;umbilical cord matrix (Mitchell et al., Stem Cells, 21:50-60, 2003),small embryonic-like stem cells (Kucia et al., J Physiol Pharmaco, 57Suppl 5:5-18, 2006), amniotic fluid stem cells (Atala, A., J TissueRegen Med 1:83-96, 2007), skin-derived precursors (Toma et al., Nat CellBiol 3:778-784, 2001), adipose tissue (U.S. 2005/0153442),gastrointestinal stem cells, epidermal stem cells, and hepatic stemcells, which also have been termed “oval cells” (Potten et al., Trans RSoc Lond B Biol Sci 353:821-830 (1998); Watt, F., Trans R Soc Lond BBiol Sci 353:831 (1997); Alison et al., Hepatology 29:678-683 (1998),and bone marrow (see U.S. Publication Nos. 2003/0059414 and2006/0147246), each of which is incorporated by reference herein forteaching these cells.

Strategies of Reprogramming Somatic Cells

Several different strategies, such as nuclear transplantation, cellularfusion, and culture induced reprogramming, have been employed to inducethe conversion of differentiated cells into an embryonic state. Thereferences cited below are incorporated by reference for teaching how tomake these cells and describing them.

Nuclear transfer involves the injection of a somatic nucleus into anenucleated oocyte, which, upon transfer into a surrogate mother, cangive rise to a clone (“reproductive cloning”), or, upon explantation inculture, can give rise to genetically matched embryonic stem (ES) cells(“somatic cell nuclear transfer,” SCNT). Cell fusion of somatic cellswith ES cells results in the generation of hybrids that show allfeatures of pluripotent ES cells. Explantation of somatic cells inculture selects for immortal cell lines that may be pluripotent ormultipotent. At present, spermatogonial stem cells are the only sourceof pluripotent cells that can be derived from postnatal animals.Transduction of somatic cells with defined factors can initiatereprogramming to a pluripotent state. These experimental approaches havebeen extensively reviewed (Hochedlinger and Jaenisch, Nature441:1061-1067 (2006) and Yamanaka, S., Cell Stem Cell 1:39-49 (2007)).

Nuclear Transfer

Nuclear transplantation (NT), also referred to as somatic cell nucleartransfer (SCNT), denotes the introduction of a nucleus from a donorsomatic cell into an enucleated oocyte to generate a cloned animal(Wilmut et al., Nature 385:810-813 (1997). The generation of liveanimals by NT demonstrated that the epigenetic state of somatic cells,including that of terminally differentiated cells, can be reprogrammedto an embryonic state.

Fusion of Somatic Cells and Embryonic Stem Cells

Epigenetic reprogramming of somatic nuclei to an undifferentiated statehas been demonstrated by fusion of embryonic cells with somatic cells.Hybrids between various somatic cells and embryonic carcinoma cells(Solter, D., Nat Rev Genet 7:319-327 (2006), embryonic germ (EG), or EScells (Zwaka and Thomson, Development 132:227-233 (2005)) share manyfeatures with the parental embryonic cells, indicating that thepluripotent phenotype is dominant in such fusion products. As with mouse(Tada et al., Curr Biol 11:1553-1558 (2001)), human ES cells have thepotential to reprogram somatic nuclei after fusion (Cowan et al.,Science 309:1369-1373(2005)); Yu et al., Science 318:1917-1920 (2006)).Activation of silent pluripotency markers, such as oct4, may occur (Doand Scholer, Stem Cells 22:941-949 (2004)). Forced overexpression ofNanog in ES cells promotes pluripotency when fused with neural stemcells (Silva et al., Nature 441:997-1001 (2006)).

Culture-Induced Reprogramming

Pluripotent cells have been derived from embryonic sources, such asblastomeres and the inner cell mass (ICM) of the blastocyst (ES cells),the epiblast (EpiSC cells), primordial germ cells (EG cells), andpostnatal spermatogonial stem cells (“maGSCsm” “ES-like” cells). Thefollowing pluripotent cells, along with their donor cell/tissue is asfollows: parthogenetic ES cells are derived from murine oocytes(Narasimha et al., Curr Biol 7:881-884 (1997)); embryonic stem cellshave been derived from blastomeres (Wakayama et al., Stem Cells25:986-993 (2007)); inner cell mass cells (source not applicable) (Egganet al., Nature 428:44-49 (2004)); embryonic germ and embryonal carcinomacells have been derived from primordial germ cells (Matsui et al., Cell,70:841-847 (1992)); GMCS, maSSC, and MASC have been derived fromspermatogonial stem cells (Guan et al., Nature, 440:1199-1203 (2006);Kanatsu-Shinohara et al., Cell 119:1001-1012 (2004); and Seandel et al.,Nature 449:346-350 (2007)); EpiSC cells are derived from epiblasts(Brons et al., Nature 448:191-195 (2007); Tesar et al., Nature,448:196-199(2007)); parthogenetic ES cells have been derived from humanoocytes (Cibelli et al., Science 295L819 (2002); Revazova et al.,Cloning Stem Cells 9:432-449 (2007)); human ES cells have been derivedfrom human blastocysts (Thomson et al., Science 282:1145-1147 (1998));MAPC have been derived from bone marrow (Jiang et al., Nature, 418:41-49(2002); Phinney and Prockop, Stem Cells 25:2896-2902 (2007)); cord bloodcells (derived from cord blood) (van de Ven et al., Exp Hematol35:1753-1765 (2007)); neurosphere derived cells derived from neural cell(Clarke et al., Science, 288:1660-1663 (2000)). Donor cells from thegerm cell lineage such as PGCs or spermatogonial stem cells are known tobe unipotent in vivo, but it has been shown that pluripotent ES-likecells (Kanatsu-Shinohara et al., Cell, 119:1001-1012 (2004) or maGSCs(Guan et al., Nature 440:1199-1203 (2006), can be isolated afterprolonged in vitro culture. While most of these pluripotent cell typeswere capable of in vitro differentiation and teratoma formation, onlyES, EG, EC, and the spermatogonial stem cell-derived maGCSs or ES-likecells were pluripotent by more stringent criteria, as they were able toform postnatal chimeras and contribute to the germline Recently,multipotent adult spermatogonial stem cells (MASCs) were derived fromtesticular spermatogonial stem cells of adult mice, and these cells hadan expression profile different from that of ES cells (Seandel et al.,Nature 449:346-350 (2007)) but similar to EpiSC cells, which werederived from the epiblast of postimplantation mouse embryos (Brons etal., Nature 448:191-195 (2007); Tesar et al., Nature 448:196-199(2007)).

Reprogramming by Defined Transcription Factors

Somatic cells can be reprogrammed to an ES-like state (Takahashi andYamanaka, Cell 126:663-676 (2006)). Mouse embryonic fibroblasts (MEFs)and adult fibroblasts were programmed to pluripotent ES-like cells bytransduction of oct4, sox2, c-myc, and Klf4. Cells were called iPS(induced pluripotent stem) cells. While genetic experiments hadestablished that Oct4 and Sox2 are essential for pluripotency (Chambersand Smith, Oncogene 23:7150-7160 (2004); Ivanona et al., Nature442:5330538 (2006); Masui et al., Nat Cell Biol 9:625-635 (2007)), c-mycand Klf4 may be dispensable (Nakagawa et al., Nat Biotechnol 26:191-106(2008); Werning et al., Nature 448:318-324 (2008); Yu et al., Science318: 1917-1920 (2007)).

MAPC

An exemplary cell of the present invention has been designated “MAPC.”MAPC is an acronym for “multipotent adult progenitor cell” (non-ES,non-EG, non-germ) that has the capacity to differentiate into cell typesof all three primitive germ layers (ectoderm, mesoderm, and endoderm).Genes found in ES cells also have been found in MAPCs (e.g., telomerase,Oct 3/4, rex-1, rox-1, sox-2). Oct 3/4 (Oct 3A in humans) appears to bespecific for ES and germ cells. MAPC represents a more primitiveprogenitor cell population than MSC and demonstrates differentiationcapability encompassing the epithelial, endothelial, neural, myogenic,hematopoietic, osteogenic, hepatogenic, chondrogenic and adipogeniclineages (Verfaillie, C. M., Trends Cell Biol 12:502-8, 2002, Jahagirdaret al., Exp Hematol 29:543-56, 2001; Reyes and Verfaillie, Ann N Y AcadSci 938:231-233, 2001; Jiang et al., Exp Hematol 30896-904, 2002; andJiang et al., Nature 418:41-9, 2002). MAPCs thus emulate the broadbiological plasticity characteristic of ES cells, while maintaining theother characteristics that make non-embryonic stem cells appealing(e.g., normal karyotype and does not form teratomas).

Human MAPCs are described in U.S. Pat. No. 7,015,037 and applicationSer. No. 10/467,963, the contents of which are incorporated herein byreference for their description of MAPCs. MAPCs have been identified inother mammals. MAPCs can be isolated from multiple sources, including,but not limited to, bone marrow, placenta, umbilical cord and cordblood, muscle, brain, liver, spinal cord, blood and skin.

Isolation and Growth of MAPCs

Prior to forming aggregates, MAPCs can be isolated and cultured usingmethods disclosed herein and in U.S. Pat. No. 7,015,037, which isincorporated by reference herein for these methods.

In addition, the density at which MAPCs are cultured can vary from about100 cells/cm² to about 150 cells/cm² to about 10,000 cells/cm²,including about 200 cells/cm² to about 1500 cells/cm² to about 2000cells/cm². The density can vary between species. Additionally, optimaldensity can vary depending on culture conditions and source of cells. Itis within the skill of the ordinary artisan to determine the optimaldensity for a given set of culture conditions and cells.

Also, effective atmospheric oxygen concentrations of less than about10%, including about 3-5%, can be used at any time during the isolation,growth and differentiation.

In an embodiment specific for MAPCs, supplements are cellular factors orcomponents that allow MAPCs to retain the ability to differentiate intoall three lineages. This may be indicated by the expression of specificmarkers of the undifferentiated state. MAPCs, for example,constitutively express Oct 3/4 (Oct 3A) and maintain high levels oftelomerase. Assays for monitoring gene expression are well known in theart (e.g., RT-PCR) and can be conducted using standard methodology.

Cell Culture

Cells may be cultured in low-serum or serum-free culture medium.Serum-free medium used to culture MAPCs is described in U.S. Pat. No.7,015,037. Many cells have been grown in serum-free or low-serum medium.In this case, the medium is supplemented with one or more growthfactors. Commonly used growth factors include, but are not limited to,bone morphogenic protein, basic fibroblast growth factor,platelet-derived growth factor and epidermal growth factor. See, forexample, U.S. Pat. Nos. 7,169,610; 7,109,032; 7,037,721; 6,617,161;6,617,159; 6,372,210; 6,224,860; 6,037,174; 5,908,782; 5,766,951;5,397,706; and 4,657,866; all incorporated by reference herein forteaching growing cells in serum-free medium.

Methods of identifying and subsequently separating differentiated cellsfrom their undifferentiated counterparts can be carried out by methodswell known in the art. Cells that have been induced to differentiateusing methods of the present invention can be identified by selectivelyculturing cells under conditions whereby differentiated cells outnumberundifferentiated cells. Similarly, differentiated cells can beidentified by morphological changes and characteristics that are notpresent on their undifferentiated counterparts, such as cell size andthe complexity of intracellular organelle distribution. Alsocontemplated are methods of identifying differentiated cells by theirexpression of specific cell-surface markers such as cellular receptorsand transmembrane proteins. Monoclonal antibodies against thesecell-surface markers can be used to identify differentiated cells.Detection of these cells can be achieved through fluorescence activatedcell sorting (FACS) and enzyme-linked immunosorbent assay (ELISA). Fromthe standpoint of transcriptional upregulation of specific genes,differentiated cells often display levels of gene expression that aredifferent from undifferentiated cells. Reverse-transcription polymerasechain reaction, or RT-PCR, also can be used to monitor changes in geneexpression in response to differentiation. Whole genome analysis usingmicroarray technology also can be used to identify differentiated cells.

Accordingly, once differentiated cells are identified, they can beseparated from their undifferentiated counterparts, if necessary. Themethods of identification detailed above also provide methods ofseparation, such as FACS, preferential cell culture methods, ELISA,magnetic beads and combinations thereof. One embodiment of the presentinvention contemplates the use of FACS to identify and separate cellsbased on cell-surface antigen expression.

Pharmaceutical Formulations

Any of the cells produced by the methods described herein can be used inthe clinic to treat a subject. They can, therefore, be formulated into apharmaceutical composition. Therefore, in certain embodiments, the cellsare present within a composition adapted for and suitable for delivery,i.e., physiologically compatible. Accordingly, compositions will oftenfurther comprise one or more buffers (e.g., neutral buffered saline orphosphate buffered saline), carbohydrates (e.g., glucose, mannose,sucrose or dextrans), mannitol, proteins, polypeptides or amino acidssuch as glycine, antioxidants, bacteriostats, chelating agents such asEDTA or glutathione, adjuvants (e.g., aluminum hydroxide), solutes thatrender the formulation isotonic, hypotonic or weakly hypertonic with theblood of a recipient, suspending agents, thickening agents and/orpreservatives.

In other embodiments, cells are present within a composition adapted foror suitable for freezing or storage.

In many embodiments the purity of the cells for administration to asubject is about 100%. In other embodiments it is 95% to 100%. In someembodiments it is 85% to 95%. Particularly in the case of admixtureswith other cells, the percentage can be about 10%-15%, 15%-20%, 20%-25%,25%-30%, 30%-35%, 35%-40%, 40%-45%, 45%-50%, 60%-70%, 70%-80%, 80%-90%,or 90%-95%. Or isolation/purity can be expressed in terms of celldoublings where the cells have undergone, for example, 10-20, 20-30,30-40, 40-50 or more cell doublings.

The numbers of cells in a given volume can be determined by well knownand routine procedures and instrumentation. The percentage of the cellsin a given volume of a mixture of cells can be determined by much thesame procedures. Cells can be readily counted manually or by using anautomatic cell counter. Specific cells can be determined in a givenvolume using specific staining and visual examination and by automatedmethods using specific binding reagent, typically antibodies,fluorescent tags, and a fluorescence activated cell sorter.

The choice of formulation for administering the cells for a givenapplication will depend on a variety of factors. Prominent among thesewill be the species of subject, the nature of the disorder, dysfunction,or disease being treated and its state and distribution in the subject,the nature of other therapies and agents that are being administered,the optimum route for administration, survivability via the route, thedosing regimen, and other factors that will be apparent to those skilledin the art. In particular, for instance, the choice of suitable carriersand other additives will depend on the exact route of administration andthe nature of the particular dosage form.

For example, cell survival can be an important determinant of theefficacy of cell-based therapies. This is true for both primary andadjunctive therapies. Another concern arises when target sites areinhospitable to cell seeding and cell growth. This may impede access tothe site and/or engraftment there of therapeutic cells. Variousembodiments of the invention comprise measures to increase cell survivaland/or to overcome problems posed by barriers to seeding and/or growth.

Final formulations of the aqueous suspension of cells/medium willtypically involve adjusting the ionic strength of the suspension toisotonicity (i.e., about 0.1 to 0.2) and to physiological pH (i.e.,about pH 6.8 to 7.5). The final formulation will also typically containa fluid lubricant, such as maltose, which must be tolerated by the body.Exemplary lubricant components include glycerol, glycogen, maltose andthe like. Organic polymer base materials, such as polyethylene glycoland hyaluronic acid as well as non-fibrillar collagen, preferablysuccinylated collagen, can also act as lubricants. Such lubricants aregenerally used to improve the injectability, intrudability anddispersion of the injected biomaterial at the site of injection and todecrease the amount of spiking by modifying the viscosity of thecompositions. This final formulation is by definition the cells in apharmaceutically-acceptable carrier.

The cells are subsequently placed in a syringe or other injectionapparatus for precise placement at the site of the tissue defect. Theterm “injectable” means the formulation can be dispensed from syringeshaving a gauge as low as 25 under normal conditions under normalpressure without substantial spiking Spiking can cause the compositionto ooze from the syringe rather than be injected into the tissue. Forthis precise placement, needles as fine as 27 gauge (200μ I.D.) or even30 gauge (150μ I.D.) are desirable. The maximum particle size that canbe extruded through such needles will be a complex function of at leastthe following: particle maximum dimension, particle aspect ratio(length:width), particle rigidity, surface roughness of particles andrelated factors affecting particle:particle adhesion, the viscoelasticproperties of the suspending fluid, and the rate of flow through theneedle. Rigid spherical beads suspended in a Newtonian fluid representthe simplest case, while fibrous or branched particles in a viscoelasticfluid are likely to be more complex.

The desired isotonicity of the compositions of this invention may beaccomplished using sodium chloride, or other pharmaceutically-acceptableagents such as dextrose, boric acid, sodium tartrate, propylene glycol,or other inorganic or organic solutes. Sodium chloride is preferredparticularly for buffers containing sodium ions.

Viscosity of the compositions, if desired, can be maintained at theselected level using a pharmaceutically-acceptable thickening agent.Methylcellulose is preferred because it is readily and economicallyavailable and is easy to work with. Other suitable thickening agentsinclude, for example, xanthan gum, carboxymethyl cellulose,hydroxypropyl cellulose, carbomer, and the like. The preferredconcentration of the thickener will depend upon the agent selected. Theimportant point is to use an amount, which will achieve the selectedviscosity. Viscous compositions are normally prepared from solutions bythe addition of such thickening agents.

A pharmaceutically-acceptable preservative or stabilizer can be employedto increase the life of cell/medium compositions. If such preservativesare included, it is well within the purview of the skilled artisan toselect compositions that will not affect the viability or efficacy ofthe cells.

Those skilled in the art will recognize that the components of thecompositions should be chemically inert. This will present no problem tothose skilled in chemical and pharmaceutical principles. Problems can bereadily avoided by reference to standard texts or by simple experiments(not involving undue experimentation) using information provided by thedisclosure, the documents cited herein, and generally available in theart.

Sterile injectable solutions can be prepared by incorporating the cellsutilized in practicing the present invention in the required amount ofthe appropriate solvent with various amounts of the other ingredients,as desired.

In some embodiments, cells are formulated in a unit dosage injectableform, such as a solution, suspension, or emulsion. Pharmaceuticalformulations suitable for injection of cells typically are sterileaqueous solutions and dispersions. Carriers for injectable formulationscan be a solvent or dispersing medium containing, for example, water,saline, phosphate buffered saline, polyol (for example, glycerol,propylene glycol, liquid polyethylene glycol, and the like), andsuitable mixtures thereof.

The skilled artisan can readily determine the amount of cells andoptional additives, vehicles, and/or carrier in compositions to beadministered in methods of the invention. Typically, any additives (inaddition to the cells) are present in an amount of 0.001 to 50 wt % insolution, such as in phosphate buffered saline. The active ingredient ispresent in the order of micrograms to milligrams, such as about 0.0001to about 5 wt %, preferably about 0.0001 to about 1 wt %, mostpreferably about 0.0001 to about 0.05 wt % or about 0.001 to about 20 wt%, preferably about 0.01 to about 10 wt %, and most preferably about0.05 to about 5 wt %.

In some embodiments cells are encapsulated for administration,particularly where encapsulation enhances the effectiveness of thetherapy, or provides advantages in handling and/or shelf life.Encapsulation in some embodiments where it increases the efficacy ofcell mediated immunosuppression may, as a result, also reduce the needfor immunosuppressive drug therapy.

Also, encapsulation in some embodiments provides a barrier to asubject's immune system that may further reduce a subject's immuneresponse to the cells (which generally are not immunogenic or are onlyweakly immunogenic in allogeneic transplants), thereby reducing anygraft rejection or inflammation that might occur upon administration ofthe cells.

Cells may be encapsulated by membranes, as well as capsules, prior toimplantation. It is contemplated that any of the many methods of cellencapsulation available may be employed. In some embodiments, cells areindividually encapsulated. In some embodiments, many cells areencapsulated within the same membrane. In embodiments in which the cellsare to be removed following implantation, a relatively large sizestructure encapsulating many cells, such as within a single membrane,may provide a convenient means for retrieval.

A wide variety of materials may be used in various embodiments formicroencapsulation of cells. Such materials include, for example,polymer capsules, alginate-poly-L-lysine-alginate microcapsules, bariumpoly-L-lysine alginate capsules, barium alginate capsules,polyacrylonitrile/polyvinylchloride (PAN/PVC) hollow fibers, andpolyethersulfone (PES) hollow fibers.

Techniques for microencapsulation of cells that may be used foradministration of cells are known to those of skill in the art and aredescribed, for example, in Chang et al., 1999; Matthew et al., 1991;Yanagi et al., 1989; Cai et al., 1988; Chang, T. M., 1992 and in U.S.Pat. No. 5,639,275 (which, for example, describes a biocompatiblecapsule for long-term maintenance of cells that stably expressbiologically active molecules. Additional methods of encapsulation arein European Patent Publication No. 301,777 and U.S. Pat. Nos. 4,353,888;4,744,933; 4,749,620; 4,814,274; 5,084,350; 5,089,272; 5,578,442;5,639,275; and 5,676,943. All of the foregoing are incorporated hereinby reference in parts pertinent to encapsulation of cells.

Certain embodiments incorporate cells into a polymer, such as abiopolymer or synthetic polymer. Examples of biopolymers include, butare not limited to, fibronectin, fibrin, fibrinogen, thrombin, collagen,and proteoglycans. Other factors, such as the cytokines discussed above,can also be incorporated into the polymer. In other embodiments of theinvention, cells may be incorporated in the interstices of athree-dimensional gel. A large polymer or gel, typically, will besurgically implanted. A polymer or gel that can be formulated in smallenough particles or fibers can be administered by other common, moreconvenient, non-surgical routes.

In the case of treating liver deficiency, in particular, the cells maybe enclosed in a device that can be implanted in a subject. Cells can beimplanted in or near the liver or elsewhere to replace or supplementliver function. Cells can also be implanted without being in a device,e.g., in existing liver tissue.

Dosing

Compositions can be administered in dosages and by techniques well knownto those skilled in the medical and veterinary arts taking intoconsideration such factors as the age, sex, weight, and condition of theparticular patient, and the formulation that will be administered (e.g.,solid vs. liquid). Doses for humans or other mammals can be determinedwithout undue experimentation by the skilled artisan, from thisdisclosure, the documents cited herein, and the knowledge in the art.

The dose of cells appropriate to be used in accordance with variousembodiments of the invention will depend on numerous factors. It mayvary considerably for different circumstances. The parameters that willdetermine optimal doses to be administered for primary and adjunctivetherapy generally will include some or all of the following: the diseasebeing treated and its stage; the species of the subject, their health,gender, age, weight, and metabolic rate; the subject's immunocompetence;other therapies being administered; and expected potential complicationsfrom the subject's history or genotype. The parameters may also include:whether the cells are syngeneic, autologous, allogeneic, or xenogeneic;their potency (specific activity); the site and/or distribution thatmust be targeted for the cells to be effective; and such characteristicsof the site such as accessibility to cells and/or engraftment of cells.Additional parameters include co-administration with other factors (suchas growth factors and cytokines). The optimal dose in a given situationalso will take into consideration the way in which the cells areformulated, the way they are administered, and the degree to which thecells will be localized at the target sites following administration.Finally, the determination of optimal dosing necessarily will provide aneffective dose that is neither below the threshold of maximal beneficialeffect nor above the threshold where the deleterious effects associatedwith the dose outweighs the advantages of the increased dose.

The optimal dose of cells for some embodiments will be in the range ofdoses used for autologous, mononuclear bone marrow transplantation. Forfairly pure preparations of cells, optimal doses in various embodimentswill range from 10⁴ to 10⁸ cells/kg of recipient mass peradministration. In some embodiments the optimal dose per administrationwill be between 10⁵ to 10⁷ cells/kg. In many embodiments the optimaldose per administration will be 5×10⁵ to 5×10⁶ cells/kg. By way ofreference, higher doses in the foregoing are analogous to the doses ofnucleated cells used in autologous mononuclear bone marrowtransplantation. Some of the lower doses are analogous to the number ofCD34⁺ cells/kg used in autologous mononuclear bone marrowtransplantation.

It is to be appreciated that a single dose may be delivered all at once,fractionally, or continuously over a period of time. The entire dosealso may be delivered to a single location or spread fractionally overseveral locations.

In various embodiments, cells may be administered in an initial dose,and thereafter maintained by further administration. Cells may beadministered by one method initially, and thereafter administered by thesame method or one or more different methods. The levels can bemaintained by the ongoing administration of the cells. Variousembodiments administer the cells either initially or to maintain theirlevel in the subject or both by intravenous injection. In a variety ofembodiments, other forms of administration, are used, dependent upon thepatient's condition and other factors, discussed elsewhere herein.

It is noted that human subjects are treated generally longer thanexperimental animals; but, treatment generally has a length proportionalto the length of the disease process and the effectiveness of thetreatment. Those skilled in the art will take this into account in usingthe results of other procedures carried out in humans and/or in animals,such as rats, mice, non-human primates, and the like, to determineappropriate doses for humans. Such determinations, based on theseconsiderations and taking into account guidance provided by the presentdisclosure and the prior art will enable the skilled artisan to do sowithout undue experimentation.

Suitable regimens for initial administration and further doses or forsequential administrations may all be the same or may be variable.Appropriate regimens can be ascertained by the skilled artisan, fromthis disclosure, the documents cited herein, and the knowledge in theart.

The dose, frequency, and duration of treatment will depend on manyfactors, including the nature of the disease, the subject, and othertherapies that may be administered. Accordingly, a wide variety ofregimens may be used to administer the cells/medium.

In some embodiments cells are administered to a subject in one dose. Inothers cells are administered to a subject in a series of two or moredoses in succession. In some other embodiments wherein cells areadministered in a single dose, in two doses, and/or more than two doses,the doses may be the same or different, and they are administered withequal or with unequal intervals between them.

Cells may be administered in many frequencies over a wide range oftimes. In some embodiments, they are administered over a period of lessthan one day. In other embodiment they are administered over two, three,four, five, or six days. In some embodiments they are administered oneor more times per week, over a period of weeks. In other embodimentsthey are administered over a period of weeks for one to several months.In various embodiments they may be administered over a period of months.In others they may be administered over a period of one or more years.Generally lengths of treatment will be proportional to the length of thedisease process, the effectiveness of the therapies being applied, andthe condition and response of the subject being treated.

Uses

Useful cells are in aggregate form or in cells derived from theaggregate. Large numbers of cells can be produced by aggregation methodsbut the cells that are further used can be removed, e.g., dis-aggregatedor dispersed from the aggregate. So, for example, pharmaceuticalcompositions can comprise the cells in aggregate form or derived fromthe aggregate (e.g., by dispersion). Likewise, differentiation factorscan be applied to the cells in aggregate form or to cells derived fromthe aggregate. Pharmaceutical compositions can, therefore, be made withdifferentiated cells formed by applying differentiation conditions tothe aggregate or to cells derived from the aggregate. Further, clinicaluses described below pertain to the in vivo use of the undifferentiatedaggregates and undifferentiated cells derived from the aggregates aswell as differentiated progeny of the aggregates and differentiatedprogeny of cells derived from the aggregates. Undifferentiated cells areuseful, like their differentiated progeny, because they may give rise tothose progeny in vivo. (Undifferentiated cells may be useful even whenthey do not differentiate, for other beneficial purposes, such asangiogenic, immunomodulatory, cytogenic, trophic, etc.).

The aggregated cells or cells derived from the aggregates may have thecapacity to be induced to differentiate to form at least onedifferentiated cell type of mesodermal, neurectodermal and endodermalorigin. For example, the cells may have the capacity to be induced todifferentiate to form cells of at least osteoblast, chondrocyte,adipocyte, fibroblast, marrow stroma, skeletal muscle, smooth muscle,cardiac muscle, endothelial, epithelial, hematopoietic, glial, neuronalor oligodendrocyte cell type.

The invention further provides differentiated cells obtained from thecells described above, wherein the progeny cell may be a bone,cartilage, adipocyte, fibroblast, marrow stroma, skeletal muscle, smoothmuscle, cardiac muscle, endothelial, epithelial, endocrine, exocrine,hematopoietic, glial, neuronal or oligodendrocyte cell. Thedifferentiated progeny cell may be a skin epithelial cell, liverepithelial cell, pancreas epithelial cell, pancreas endocrine cell orislet cell, pancreas exocrine cell, gut epithelium cell, kidneyepithelium cell, or an epidermal associated structure.

The cells or their differentiated progeny can be used to correct agenetic disease, degenerative disease, cardiovascular disease, metabolicstorage disease, neural, or cancer disease process. They can be used toproduce gingiva-like material for treatment of periodontal disease. Theycan be used to develop skin epithelial tissue derived from the cellsthat can be utilized for skin grafting and plastic surgery. They can beused to enhance muscle, such as in the penis or heart. They can be usedto produce blood ex vivo for therapeutic use, or to produce humanhematopoietic cells and/or blood in prenatal or post natal animals forhuman use. They can be used as a therapeutic to aid for example in therecovery of a patient from chemotherapy or radiation therapy intreatment of cancer, in the treatment of autoimmune disease, to inducetolerance in the recipient. They can be used to treat AIDS or otherinfectious diseases.

Neuroretinal cells can be used to treat blindness caused by among otherthings but not limited to neuroretinal disease caused by among otherthings macular degeneration, diabetic retinopathy, glaucoma, retinitispigmentosa.

The cells or cardiomyocytes derived from the cells can be used to treatcardiac diseases including, but not limited to, myocarditis,cardiomyopathy, heart failure, damage caused by heart attacks,hypertension, atherosclerosis, and heart valve dysfunction. They alsocan be used to treat a disease involving CNS deficits or damage. Furtherthe stem cell, or its neuronally differentiated progeny cell, can beused to treat a disease involving neural deficits or degenerationincluding, but not limited to, stroke, Alzheimer's disease, Parkinson'sdisease, Huntington's disease, AIDS-associated dementia, spinal cordinjury, and metabolic diseases affecting the brain or other nervoustissue.

Cells or their differentiated progeny, such as stromal cells, can beused to support the growth and differentiation of other cell types invivo or in vitro, including, but not limited to, hematopoietic cells,pancreatic islet or beta cells, hepatocytes, and the like. The cells ordifferentiated cartilage progeny, can be used to treat a disease of thejoints or cartilage, including, but not limited to, cartilage tears,cartilage thinning, and osteoarthritis. Moreover, the cells or theirdifferentiated osteoblast progeny can be used to ameliorate a processhaving deleterious effects on bone including, but not limited to, bonefractures, non-healing fractures, osteoarthritis, “holes” in bones causeby tumors spreading to bone such as prostate, breast, multiple myeloma,and the like.

Using appropriate growth factors, chemokines, and cytokines, cells canbe induced to differentiate to form a number of lineages, including, forexample, a variety of cells of mesodermal phenotype, cells ofneuroectodermal phenotype (glial cells, oligodendrocytes, and neurons),and cells of endodermal phenotype. These include osteoblasts,chondroblasts, adipocyte, cartilage and bone, skeletal muscle, smoothmuscle, cardiac muscle, endothelial cells, hematopoietic cells, stromalcells, neuronal cells, and epithelial cells.

Osteoblasts:

Cells that have been induced to differentiate to form bone cells can beused as cell therapy or for tissue regeneration in osteoporosis, Paget'sdisease, bone fracture, osteomyelitis, osteonecrosis, achondroplasia,osteogenesis imperfecta, hereditary multiple exostosis, multipleepiphyseal dysplasia, Marfan's syndrome, mucopolysaccharidosis,neurofibromatosis or scoliosis, reconstructive surgery for localizedmalformations, spina bifida, hemivertebrae or fused vertebrae, limbanomalies, reconstruction of tumor-damaged tissue, and reconstructionafter infection, such as middle ear infection.

Chondrocytes:

Cells that have been induced to differentiate to form cartilage cellscan be used for cell therapy or tissue regeneration in age-relateddiseases or injuries, in sports-related injuries, or in specificdiseases, such as rheumatoid arthritis, psoriasis arthritis, Reiter'sarthritis, ulcerative colitis, Crohn's disease, ankylosing spondylitis,osteoarthritis, reconstructive surgery of the outer ear, reconstructivesurgery of the nose, and reconstructive surgery of the cricoidcartilage.

Adipocytes:

Cells that have been induced to differentiate to form adipocytes can beused in resculpting for reconstructive or cosmetic surgery, includingbut not limited to, breast reconstruction after mastectomy, reshapingtissue lost as a result of other surgery, such as tumor removal from theface or hand, breast augmentation, and reduction of wrinkles. Treatmentof Type II diabetes is also applicable. Adipocytes thus derived can alsoprovide an effective in vitro model system for the study of fatregulation.

Fibroblasts:

Fibroblasts derived from the cells can be used for cell therapy ortissue repair to promote wound healing or to provide connective tissuesupport, such as scaffolding for cosmetic surgery.

Skeletal Muscle:

Cells that have been be induced to differentiate to form skeletal musclecells can be used for cell therapy or tissue repair in the treatment ofDuchenne muscular dystrophy, Becker muscular dystrophy, myotonicdystrophy, skeletal myopathy, and reconstructive surgery to repairskeletal muscle damage.

Smooth Muscle:

Cells that have been induced to differentiate to form smooth musclecells can be used for cell therapy or tissue repair in the treatment ofdevelopmental abnormalities of the gastrointestinal system, such asoesophageal atresia, intestinal atresia, and intussusception, andreplacement of tissues after surgery for bowel infarction or colostomy.Smooth muscle cells can also be used for bladder or uterinereconstruction, neovascularization, repair of vessels damaged by, forexample, atherosclerosis or aneurysm. Smooth muscle precursor cells(mesangial cells) can be used as an in vitro model for glomerulardiseases or for cell therapy or tissue regeneration in diabeticneuropathy. Smooth muscle precursors can also be used to repair maculadensa of the distal convoluted tubule or juxtaglomerular tissues.

Cardiomyocytes:

Cardiomyocytes can be used for cell therapy or tissue repair fortreating heart tissue damaged following myocardial infarction, inconjunction with congestive heart failure, during valve replacement, bycongenital heart anomalies, or resulting from cardiomyopathies orendocarditis.

Microglial Cells:

Microglial cells can be used to treat spinal cord injuries andneurodegenerative disorders, such as Huntington's disease, Parkinson'sdisease, multiple sclerosis, and Alzheimer's disease, as well as repairof tissues damaged during infectious disease affecting the centralnervous system. Microglial cells that have been genetically altered toproduce cytokines can also be used for transplantation for the treatmentof infectious disease in the central nervous system where access islimited due to the blood-brain barrier. Glial cells can also be used toproduce growth factors or growth factor inhibitors for regeneration ofnerve tissue after stroke, as a consequence of multiple sclerosis,amylotropic lateral sclerosis, and brain cancer, and for regenerationafter spinal cord injury.

Stromal Cells:

Stromal cells can be used as transplant cells for post-chemotherapy bonemarrow replacement and bone marrow transplantation.

Endothelial Cells:

Endothelial cells can be used in the treatment of Factor VIII deficiencyand to produce angiogenesis for neovascularization. Endothelial cellscan also provide an in vitro model for tumor suppression usingangiogenic inhibitors, as well as an in vitro model for vasculitis,hypersensitivity and coagulation disorders.

Hematopoietic Cells:

Hematopoietic cells can be used to repopulate the bone marrow afterhigh-dose chemotherapy. Hematopoietic cells derived from the cells ofthe aggregate can be further differentiated to form blood cells to bestored in blood banks, alleviating the problem of a limited supply ofblood for transfusions.

Neuroectodermal Cells:

Microglial cells can be used to treat spinal cord injuries andneurodegenerative disorders, such as Huntington's disease, Parkinson'sdisease, multiple sclerosis, and Alzheimer's disease, as well as repairof tissues damaged during infectious disease affecting the centralnervous system. Microglial cells that have been genetically altered toproduce cytokines can also be used for transplantation for the treatmentof infectious disease in the central nervous system where access islimited due to the blood-brain barrier. Glial cells can also be used toproduce growth factors or growth factor inhibitors for regeneration ofnerve tissue after stroke, as a consequence of multiple sclerosis,amylotropic lateral sclerosis, and brain cancer, as well as forregeneration after spinal cord injury. Cells induced to formoligodendrocytes and astrocytes, for example, can be used for transplantinto demyelinated tissues, especially spinal cord, where they functionto myelinate the surrounding nervous tissues. The cells also can be usedin cell replacement therapy and/or gene therapy to treat congenitalneurodegenerative disorders or storage disorders such as, for instance,mucopolysaccharidosis, leukodystrophies (globoid-cell leukodystrophy,Canavan's disease), fucosidosis, GM2 gangliosidosis, Niemann-Pick,Sanfilippo syndrome, Wolman's disease, and Tay Sachs. They can also beused for traumatic disorders such as stroke, CNS bleeding, and CNStrauma; for peripheral nervous system disorders such as spinal cordinjury or syringomyelia; for retinal disorders such as retinaldetachment, macular degeneration and other degenerative retinaldisorders, and diabetic retinopathy.

Ectodermal Epithelial Cells:

Cells can be used in cell replacement therapy and/or gene therapy totreat or alleviate symptoms of skin disorders such as alopecia, skindefects such as burn wounds, and albinism.

Endodermal Epithelial Cells:

Epithelial cells can be used in cell replacement therapy and/or genetherapy to treat or alleviate symptoms of several organ diseases. Thecells could be used to treat or alleviate congenital liver disorders,for example, storage disorders such as mucopolysaccharidosis,leukodystrophies, GM2 gangliosidosis; increased bilirubin disorders, forinstance Crigler-Najjar syndrome; ammonia disorders, such as inbornerrors of the urea-cycle, for instance ornithine decarboxylasedeficiency, citrullinemia, and arginosuccinic aciduria; inborn errors ofamino acids and organic acids, such as phenylketonuria, hereditarytyrosinemia, and alphal-antitrypsin deficiency; and coagulationdisorders such as factor VIII and IX deficiency. The cells can also beused to treat acquired liver disorders that result from viralinfections. The cells can also be used in ex vivo applications, such asto generate an artificial liver, to produce coagulation factors and toproduce proteins or enzymes generated by liver epithelium. Theepithelial cells can also be used in cell replacement therapy and/orgene therapy to treat or alleviate symptoms of biliary disorders, suchas biliary cirrhosis and biliary atresia. The epithelial cells can alsobe used in cell replacement therapy and/or gene therapy to treat oralleviate symptoms of pancreatic disorders, such as pancreatic atresia,pancreas inflammation, and alphal-antitrypsin deficiency. Further, aspancreatic epithelium, and as neural cells can be made, beta-cells canbe generated. These cells can be used for the therapy of diabetes(subcutaneous implantation or intra-pancreas or intra-liverimplantation. Further, the epithelial cells can also be used in cellreplacement therapy and/or gene therapy to treat or alleviate symptomsof gut epithelium disorders such as gut atresia, inflammatory boweldisorders, bowel infarcts, and bowel resection.

Cells are Useful for Tissue Repair:

Cells can also be used for tissue repair. Cells can be implanted intobone to enhance the repair process, to reinforce weakened bone, or toresurface joints. Chondrocytes can be injected into joints to resurfacejoint cartilage. Caplan et al. (U.S. Pat. No. 5,855,619) describe abiomatrix implant including a contracted gel matrix into whichmesenchymal stem cells have been incorporated. The implant is designedfor repair of a tissue defect, especially for injury to tendon,ligament, meniscus, or muscle. Cartilage, for example, can be formed bythe addition of chondrocytes in the immediate area around a porous,3-dimensional scaffold made, for example, of collagen, syntheticpolyglycolic acid fibers, or synthetic polylactic fibers. The inventorshave shown that cells of the present invention differentiate to formchondrocytes, for example, which can be deposited in and around acollagen, synthetic polyglycolic, or synthetic polylactic or otherscaffold material to provide an implant to facilitate tissue repair.

Cells can be used to produce tissues or organs for transplantation.Oberpenning et al. (Nature Biotechnology 17:149-155 (1999)) reported theformation of a working bladder by culturing muscle cells from theexterior canine bladder and lining cells from the interior of the caninebladder, preparing sheets of tissue from these cultures, and coating asmall polymer sphere with muscle cells on the outside and lining cellson the inside. The sphere was then inserted into a dog's urinary system,where it began to function as a bladder. Nicklason et al. (Science 284:489-493 (1999)), reported the production of lengths of vascular graftmaterial from cultured smooth muscle and endothelial cells. Othermethods for forming tissue layers from cultured cells are known to thoseof skill in the art (see, for example, Vacanti et al., U.S. Pat. No.5,855,610).

For the purposes described herein, autologous, allogeneic, or xenogeneiccells can be administered to a patient, either in differentiated orundifferentiated form, genetically altered or unaltered, by directinjection to a tissue site, systemically, on or around the surface of anacceptable matrix, or in combination with a pharmaceutically-acceptablecarrier.

Model System for Studying Differentiation Pathways

The invention provides a method of using the aggregates or cells derivedfrom the aggregates to characterize cellular responses to biologic orpharmacologic agents involving contacting the cells with one or morebiologic or pharmacologic agents and identifying one or more cellularresponses to the one or more biologic or pharmacologic agents. Suchagents may have various activities. They could affect differentiation,metabolism, gene expression, viability, and the like. The cells areuseful, therefore, for e.g., toxicity testing and identifyingdifferentiation factors.

Cells of the present invention are useful for further research intodevelopmental processes, as well. Ruley et al. (WO 98/40468), forexample, have described vectors and methods for inhibiting expression ofspecific genes, as well as obtaining the DNA sequences of thoseinhibited genes. Cells of the present invention can be treated with thevectors such as those described by Ruley, which inhibit the expressionof genes that can be identified by DNA sequence analysis. The cells canthen be induced to differentiate and the effects of the alteredgenotype/phenotype can be characterized.

Hahn et al. (Nature 400: 464-468 (1999)) demonstrated, for example, thatnormal human epithelial fibroblast cells can be induced to undergotumorigenic conversion when a combination of genes, previouslycorrelated with cancer, were introduced into the cells.

Control of gene expression using vectors containing inducible expressionelements provides a method for studying the effects of certain geneproducts upon cell differentiation. Inducible expression systems areknown to those of skill in the art. One such system is theecdysone-inducible system described by No et al. (Proc. Natl. Acad. Sci.USA 93:3346-3351 (1996).

Cells can be used to study the effects of specific genetic alterations,toxic substances, chemotherapeutic agents, or other agents on thedevelopmental pathways. Tissue culture techniques known to those ofskill in the art allow mass culture of hundreds of thousands of cellsamples from different individuals, providing an opportunity to performrapid screening of compounds suspected to be, for example, teratogenicor mutagenic.

For studying developmental pathways, cells can be treated with specificgrowth factors, cytokines, or other agents, including suspectedteratogenic chemicals. Cells can also be genetically modified usingmethods and vectors known in the art. Furthermore, cells can be alteredusing antisense technology or treatment with proteins introduced intothe cell to alter expression of native gene sequences. Signal peptidesequences, for example, can be used to introduce desired peptides orpolypeptides into the cells. A particularly effective technique forintroducing polypeptides and proteins into the cell has been describedby Rojas, et al., in Nature Biotechnology 16:370-375 (1998). This methodproduces a polypeptide or protein product that can be introduced intothe culture media and translocated across the cell membrane to theinterior of the cell. Any number of proteins can be used in this mannerto determine the effect of the target protein upon the differentiationof the cell. Alternately, the technique described by Phelan et al.(Nature Biotech. 16:440-443 (1998)) can be used to link the herpes virusprotein VP22 to a functional protein for import into the cell.

Cells can also be genetically engineered, by the introduction of foreignDNA or by silencing or excising genomic DNA, to produce differentiatedcells with a defective phenotype in order to test the effectiveness ofpotential chemotherapeutic agents or gene therapy vectors.

Kits

Cells can be provided in kits, with appropriate packaging material. Forexample, cells can be provided as frozen stocks, accompanied byseparately packaged appropriate factors and media, as previouslydescribed herein, for culture in normal monolayer and/or as aggregatesin the undifferentiated state. Additionally, separately packaged factorsfor induction of differentiation can also be provided.

Differentiation to Hepatic Phenotypes

The invention is also specifically directed to methods for culturingcells so that the cells are induced to differentiate into cells thatexpress a hepatocyte phenotype and/or hepatocyte progenitor phenotype.More particularly, the invention relates to methods for culturing cellsso that the cells are induced to differentiate into cells that express adefinitive endodermal phenotype, a liver-committed endodermal phenotype,a hepatoblast phenotype, and hepatocyte phenotype. The invention is alsodirected to cells produced by the methods of the invention. The cellsare useful, among other things, for treatment of liver deficiency, livermetabolism studies, and liver toxicity studies. Culture methods aredescribed in PCT/US08/82108, incorporated herein by reference forteaching these methods. Specific culture conditions are, for example, asin the following numbered statements:

1. A method for inducing cells to differentiate into cells with ahepatocyte phenotype, comprising:

(a) culturing cells with about 5 ng/ml to about 500 ng/ml Wnt3a andabout 10 ng/ml to about 1,000 ng/ml ActivinA;

(b) then culturing the cells of step (a) with about 1 ng/ml to about 100ng/ml bFGF and about 5 ng/ml to about 500 ng/ml BMP4;

(c) then culturing the cells of step (b) with about 5 ng/ml to about 500ng/ml aFGF, about 1 ng/ml to about 100 ng/ml FGF4 and about 2.5 ng/ml toabout 250 ng/ml FGF8b; and

(d) then culturing the cells of step (c) with about 2 ng/ml to about 200ng/ml HGF and about 10 ng/ml to about 1,000 ng/ml Follistatin.

2. The method of statement 1, wherein the cells are cultured in step (a)with about 50 ng/ml Wnt3a and about 100 ng/ml ActivinA.

3. The method of statement 1, wherein the cells are cultured in step (b)with about 10 ng/ml bFGF and about 50 ng/ml BMP4.

4. The method of statement 1, wherein the cells are cultured in step (c)with about 50 ng/ml aFGF, about 10 ng/ml FGF4 and about 25 ng/ml FGF8b.

5. The method of statement 1, wherein the cells are cultured in step (d)with about 20 ng/ml HGF and about 100 ng/ml Follistatin.

6. A method for inducing cells to differentiate into cells with ahepatocyte phenotype, comprising:

(a) culturing the cells with about 50 ng/ml Wnt3a and about 100 ng/mlActivinA;

(b) then culturing the cells of step (a) with about 10 ng/ml bFGF andabout 50 ng/ml BMP4;

(c) then culturing the cells of step (b) with about 50 ng/ml aFGF, about10 ng/ml FGF4 and about 25 ng/ml FGF8b; and

(d) then culturing the cells of step (c) with about 20 ng/ml HGF andabout 100 ng/ml Follistatin.

The starting cells can have a primitive endodermal phenotype. Subsequentsteps (a)-(d) can produce cells with definitive endodermal phenotype,liver-committed phenotype, hepatoblast phenotype, and hepatocytephenotype, respectively.

7. The methods above, wherein the cells are cultured at one or moresteps in a medium containing a serum concentration ranging from 0% toabout 2%.

8. The method of statement 7, wherein the cells are cultured at one ormore steps in a medium containing a serum concentration of about 2%.

9. The methods above, wherein the cells are cultured at one or moresteps in a medium containing about 10⁻⁴ M to about 10⁻⁷ M dexamethasone.

10. The method of statement 9, wherein the cells are cultured at one ormore steps in a medium containing about 10⁻⁶ M dexamethasone.

11. The methods above, wherein the cells are cultured at one or moresteps for at least four days.

12. The method of statements above, wherein the cells that express aprimitive endodermal phenotype are cultured for about six days, thecells that express a definitive endodermal phenotype are cultured forabout four days, the cells that express a liver-committed endodermalphenotype are cultured for about four days, and the cells that express ahepatoblast phenotype are cultured for about seven days.

Accordingly the invention is also directed to methods of treating liverdeficiencies by administering the cells of the invention to a subjectwith the liver deficiency. Such deficiencies include, but are notlimited to, toxic liver disease, metabolic liver disease, acute livernecrosis, effects of acetaminophen, hemochromatosis, Wilson's Disease,Crigler Najar, hereditary tyrosinemia, familial intrahepatic cholestatistype 3, ornithine transcarbamylase (OTC) deficiency, and urea cycledisorder.

Further diseases include, but are not limited to, viral hepatitis,chronic viral hepatitis A, B, C, acute hepatitis A, B, C, D, E,cytomegalovirus and herpes simplex virus; liver dysfunction in otherinfectious diseases such as, without limitation, toxoplasmosis,hepatosplenic schistosomiasis, liver disease in syphilis, leptospirosisand amoebiasis; metabolic diseases such as, without limitation,haemochromatosis, Gilbert's syndrome, Dubin-Johnson syndrome and Rotor'ssyndrome; alcoholic liver disease such as, without limitation, fattyliver, fibrosis, sclerosis and cirrhosis; and toxic liver disease.

The invention will be further described by reference to the followingdetailed examples.

EXAMPLES Example 1. Self-Assembly of Multipotent Adult Progenitor Cells(MAPCs) and Differentiation to the Hepatic Lineage Background

Earlier studies have shown that spheroidal aggregate (3D) culture ofprimary hepatocytes results in the maintenance of viability andenhancement of liver specific functions over a long culture period. MAPCisolated from postnatal rat, mouse, and human bone marrow can beexpanded in vitro in 2D culture without senescence and can differentiateinto cells with morphological, phenotypic, and functionalcharacteristics of hepatocytes. The inventors investigated thepossibility that MAPCs could self-assemble into 3D aggregates anddifferentiate into hepatocytes. MAPCs were successfully induced into 3Daggregates that exhibited good viability, morphology and differentiationpotential based on expression of several endoderm markers like HNF3b,AFP, AAT, TTR and albumin. Differentiation protocols for making cellswith hepatic phenotypes has use in cell therapies. Other applicationsinclude use in drug toxicity studies, bioartificial liver support,tissue engineering, and as a model system to study development anddisease.

A four-step 21-day differentiation protocol was described above,optimized for medium components, oxygen levels and extra-cellular matrixfor efficient differentiation to cells with morphological, phenotypic,and functional characteristics of hepatocytes from MAPCs. Time-dependentexpression of endoderm genes was observed, including Goosecoid, CXCR4and HNF3b early representing the progression through definitiveendoderm, followed by AFP and transthyretin corresponding to the onsetof hepatic specification, and expression of albumin, glucose 6phosphatase (G6P), and cytochrome P450 depicting maturation at levelsexpressed in fetal liver by the end of differentiation. In addition togene expression, protein level expression of differentiated cells wasalso observed by immunohistochemistry for HNF3b, AFP, CK18 and albuminand their functional nature evaluated by albumin ELISA and PAS stainingfor glycogen storage.

Following this differentiation of MAPCs in 2D monolayer, the inventorsinvestigated the ability of MAPCs to self-assemble into 3D aggregatesand explored the possibility of enhanced differentiation. MAPCs weresuccessfully induced into 3D aggregates that exhibited good viability,morphology, and undifferentiated phenotype in terms of expression ofhigh levels of oct3/4 and lack of expression of differentiated markerswhen formed under “MAPC media” and 5% oxygen. The aggregates retainedthe ability to undergo spontaneous multi-lineage differentiation as wellas directed differentiation to the hepatic lineage with improvedexpression of HNF4a, a transcription factor, DPPIV, a bile duct protein,and CYP2B1 and G6P, functional hepatic markers in 3D compared to theirexpression in corresponding 2D differentiation. Other than the advantageof obtaining more functionally mature differentiated cells, 3D cultureprovides a unique model system for studying nascent 3D development andcan potentially help in the design of scalable culture systems that canbe monitored and controlled to enhance differentiation.

Liver cell transplantation and cellular-based therapies are emerging asviable clinical alternatives to whole organ transplantation as treatmenttherapies for acute, chronic and metabolic liver diseases. Several stemor progenitor cells have been identified from bone marrow, peripheralblood, cord blood, fetal and adult liver, and embryonic stem cells withthe potential to proliferate and differentiate into ‘hepatocyte-like’cells in vitro or in vivo. Multipotent Adult Progenitor Cells (MAPCs)isolated from postnatal rat, mouse and human bone marrow can be expandedin vitro without senescence, differentiate in vitro and in vivo, at thesingle cell level, into different cell types of the three germ layerlineages. MAPCs have the advantage of not forming teratomas whentransplanted and can be selected from autologous bone marrow without theneed for immunosuppression.

Although MAPCs have been shown to differentiate in vitro intoalbumin⁺CK18⁺ epithelial cells that secrete albumin and urea, these‘hepatocyte-like’ cells are not fully differentiated, and culturescontinue to have mixed heterogeneous population of cells. Severalstudies have shown that spheroidal aggregate (3D) culture of primaryhepatocytes resulted in enhancement of liver specific functions over along culture period. The inventors investigated the ability of MAPCs toself-assemble into 3D aggregates and explored the possibility ofdifferentiation to the hepatic lineage.

Differentiation of MAPCs to the hepatic lineage occurs as a result ofsequential array of distinct biological events similar to modular liverdevelopment during embryogenesis. A differentiation program of 20 daysin four consecutive steps can be applied including, formation of thedefinitive endoderm, specification of the ventral foregut endoderm,enrichment of bi-potential hepatic progenitors or hepatoblasts, andmaturation into functional ‘hepatocyte-like’ cells. On treating thecells with a high dexamethasone and serum-free differentiation basalmedia containing Activin A and Wnt-3a for a period of 6 days, bFGF andBMP4 between days 6-10, aFGF, FG8b and FGF4 between days 10-14 and HGFand Follistatin for the final period between 14-21 days, definitiveendoderm markers like Goosecoid and CXCR4 were transiently expressed inthe first stage and progressive increase in several endoderm markersincluding, α-fetoprotein (AFP), transthyretin (TTR), albumin, α-1antitrypsin (AAT), tyrosine aminotransferase (TAT), arginase-1 andglucose-6-phosphatase were observed at the mRNA level. Further, albuminELISA revealed increasing albumin levels in the medium with time, theprotein level expression of albumin, AFP and CK18 were confirmed byimmunohistochemistry, and glycogen storage was observed by PAS stainingThere was also evidence of the above protocol's applicability in thedifferentiation of human embryonic stem cells to cells expressing AFP,TTR and albumin at the mRNA level. Although there is evidence forexistence of some cells with the mature hepatocyte phenotype in thedifferentiation cultures, the persistent expression of AFP and CK19 atlater stages of differentiation and the expression of mesodermaltranscripts like Ve-Cadherin (endothelial cell marker) and SM22 (smoothmuscle marker) indicates the existence of a mixed population ofmesodermal cell types and ‘hepatocyte-like’ cells at different stages ofmaturity. Hence, it is was the inventors' interest to investigate thepotential of three-dimensional (3D) culture systems to facilitate thematuration of the hepatocyte precursors and the utilization ofpromoter-reporter constructs for the selection of mature hepatocytes orimmature precursors from the heterogeneous cell population.

Accordingly, the inventors identified conditions for optimal growth ofundifferentiated MAPCs in 3D spherical clusters and assessed theirdifferentiation potential to several cell types, specifically of theendodermal lineage. They found that undifferentiated MAPCs form 3Daggregates in culture and that the 3D aggregates retain the capacity todifferentiate.

Experiment

Rat MAPC clones expressing high levels of oct3/4 were used for formationof MAPC aggregates using either the hanging drop method (surface tensiondriven) or the forced aggregation method (centrifugation) over a periodof 4 days using MAPC media, MAPC media without LIF (leukemia inhibitoryfactor), or differentiation basal media in both low and high oxygenconditions. The starting cell number between 400-4000 cells/well wasused in both the methods. Upon characterization of the MAPC aggregatesformed using flow cytometry and quantitative real time polymerase chainreaction (QRT-PCR), MAPC media with LIF and low oxygen condition wasoptimum as oct3/4 mRNA expression levels was equivalent between MAPCsbefore and after aggregate formation and almost 90% of the number ofcells expressing in MAPCs (˜79%) before aggregate formation expressedoct3/4 at the protein level after formation of aggregates (˜69%).Further, the oct3/4 mRNA levels were comparable between aggregatesformed using the hanging drop method or the forced aggregation method.The aggregates also expressed GATA6, HNF3b and Goosecoid at levels thatare comparable to expression levels in MAPCs and did not show anyexpression of differentiation markers like AFP, albumin, AAT and TAT.Upon spontaneous differentiation in differentiation basal media (uponremoval of LIF, PDGF and EGF), the cell aggregates underwent spontaneousdifferentiation to express Nestin and Pax6 corresponding toneuroectoderm, Flk-1 and SM22 corresponding to mesoderm and AFP andAlbumin corresponding to the endoderm germ layer. Although all of theabove work was using rat high-oct3/4 expressing MAPCs, low-oct3/4 ratMAPCs also formed aggregates with the ability to undergo differentiationto several cell types. There is also evidence of 3D aggregates frommouse MAPC clones that also retained the expression of oct3/4 in theaggregates and subsequently underwent spontaneous differentiation upontransfer to differentiation basal media.

Upon differentiation of rat high oct3/4 MAPC aggregates using theprotocol optimized earlier for hepatocyte differentiation, the outcomeof differentiation was comparable to high density 2D differentiationthat was performed at the same time based on expression of hepaticmarkers like albumin, AFP, TTR, AAT and TAT. Therefore, it is apparentthat the 3D aggregates are capable of undergoing significant levels ofdifferentiation to the hepatic lineage starting from a ‘MAPC-like’phenotype.

Functional and structural properties of the differentiated aggregates:albumin ELISA for estimating albumin secretion rates, PAS staining forglycogen storage, immunostaining investigating the polarization intobasal, apical and lateral domains and elucidating the ultra-structuralcharacteristics using transmission electron microscopy (TEM). Inaddition, the use of these oct3/4 expressing MAPC aggregates as apotential method for scalable expansion of MAPCs also was explored.

Materials and Methods “MAPC Media”

MAPC media contained 60% (v/v) low glucose Dulbecco's Modified EagleMedia (DMEM) (11885, Gibco BRL, Carlsbad, Calif., USA), 40% (v/v)MCDB-201 (M6770, Sigma), 1% (v/v) 1× insulin-transferrin-selenium (ITS;Sigma), 1% (v/v) 1× linoleic acid bovine serum albumin (LA-BSA; Sigma),5×10⁻⁸ M dexamethasone (Sigma), 10⁻⁴ M ascorbic acid 3-phosphate(Sigma), 100 units of penicillin, 1000 units of streptomycin, 2% (v/v)fetal bovine serum (FBS; Hyclone, Logan, Utah, USA), 10 ng/ml mouseepidermal growth factor (Sigma), 10 ng/ml human platelet derived growthfactor (R&D systems, Minneapolis, Minn., USA), 0.54% 1×β-mercaptoethanol and 1000 units/ml mouse leukemia inhibitory factor.Media was sterilized using a 22-μm filter (Millipore, Billerica, Mass.,USA) and was kept at 4° C. for a maximum of 3-4 weeks.

Formation of MAPC Aggregates

MAPC aggregates were formed by using either the Hanging drop method orthe forced aggregation method. In the Hanging drop method; MAPCs wereseeded at 100-4000 cells/well of a 60-well microtitre plate (Nunc) in 20μl of MAPC medium/well. The plates were then inverted and placed in 5%oxygen 37C incubator for 4-5 days for the aggregates to form. In theforced aggregation method, 100-4000 MAPCs/well of a 96 well U bottomUltra-low attachment plate (Corning) were centrifuged at 1500 rpm, 4minutes and the cells were allowed to aggregate in a 5% oxygen 37Cincubator over the next 4-5 days.

Differentiation of MAPC Aggregates

There recently was developed a four-step, 21-day differentiationprotocol optimized for medium components, oxygen levels andextra-cellular matrix for efficient differentiation to cells withmorphological, phenotypic and functional characteristics of hepatocytesfrom MAPCs. The four-step protocol consisted of the following: (1)culturing MAPCs with 50 ng/ml Wnt3a and 100 ng/ml Activin A for sixdays; (2) then culturing the cells from step (1) with 10 ng/ml bFGF and50 ng/ml BMP4 for four days; (3) then culturing the cells from step (2)with 50 ng/ml aFGF, 10 ng/ml FGF4 and 25 ng/ml FGF8b for four days; and(4) then culturing the cells from step (3) with 20 ng/ml HGF and 100ng/ml Follistatin for seven days. In order to discriminate betweenhepatocyte- or biliary-like cells, Activin was inhibited by Follistatin.Prior to differentiation of the cells, undifferentiated MAPCs wereexpanded at large scale until several million cells were obtained. Cellsthen were plated at 50,000-60,000 cells/cm² in Matrigel (2%) coatedwells. Initially, cells were cultured in expansion medium until theyreached 80-90% confluency 16 hours later. Then, cells were washed twicewith PBS and the medium was switched to differentiation medium. Toverify whether the addition of the cytokines had a real hepatocyteinducing effect, differentiation was performed using basaldifferentiation medium only. All cells were cultured in low oxygen (5%)conditions in the basal differentiation medium, which consisted of DMEM(60%), MCDB (40%), ascorbic acid (1×), penicillin/streptomycin (1×),beta-mercaptoethanol, insulin-transferrin-selenium (ITS) (0.25×), LA-BSA(0.25×) and dexamethasone (10⁻⁶M). A high concentration of dexamethasonewas used because some hepatocyte specific genes (i.e., tyrosineaminotransferase, MRP2 and tryptophan 2,3 dioxygenase) are upregulatedby glucocorticoids, as they contain a glucocorticoid response element.In the complete absence of serum, cell death occurred. However, usingWnt3a, differentiation was induced in serum-free conditions. If nocytokines were added to the basal differentiating medium, 2% serum wasadded until day 12 and then stopped. Because high concentrations ofdexamethasone, together with insulin, can induce adipogenesis, a loweramount of insulin was used.

Example 2. Comparison of Differentiation of Rat MAPC Lines R2old and 19Under 2D and 3D Conditions

The goal of this study was to demonstrate the multi-lineagedifferentiation capability of MAPCs when grown and cultured as 3Daggregates. Two lines of rat MAPCs: R2old and 19, were used and weremaintained for a period of 16 days as 3D aggregates in MAPC maintenanceconditions: MAPC media with 5% oxygen. At the end of the 16 day period,3D aggregates were dissociated and replated onto fibronectin-coateddishes, similar to standard 2D monolayer maintenance of rat MAPCs.Subsequently, growth factor mediated differentiation to hepatocytes,endothelial cells and neural precursor cells were performed and thedifferentiations were compared to differentiations of rat MAPCs thatwere maintained in 2D monolayer culture during the same time period. Thedata in FIGS. 11 (A), (B) and (C) indicate the expression of markerscorresponding to the different cell types, by Quantitative-real time(QRT)-PCR. From the data, it appeared that the cells maintained as 3Daggregates retained the potential to undergo multi-lineagedifferentiation at levels comparable to cells maintained in 2D culture.Thus, MAPCs could be maintained in 3D culture without loss of quality,thus making it amenable to scale-up in bioreactors.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications that are within the spirit and scopeof the invention, as defined by the appended claims.

1-84. (canceled)
 85. A method comprising disaggregating cells in an aggregate, wherein the cells in the aggregate that are disaggregated are homogenous, the aggregate having been formed by exposing cells that are not embryonic stem cells, embryonic germ cells, or germ cells and express telomerase, are not tumorigenic, and have a normal karyotype, to conditions under which the cells aggregate, wherein the conditions comprise an oxygen concentration of about 1-10%, wherein the aggregate from which the disaggregated cells are derived does not originate from two-dimensional culture.
 86. The method of claim 85, wherein cells in the aggregate and cells derived from the aggregate express one or more of Oct 3/4, rex-1, rox-1, nanog, GATA6 and sox-2.
 87. The method of claim 85 or 86, wherein cells in the aggregate and cells derived from the aggregate can differentiate into cell types of at least two of the endodermal, ectodermal, mesodermal embryonic lineages.
 88. The method of claim 87, wherein cells in the aggregate and cells derived from the aggregate can differentiate into cell types of all three of the endodermal, ectodermal and mesodermal embryonic lineages.
 89. The method of claim 85, wherein the non-embryonic stem, non-germ cells are human cells.
 90. The method of claim 86, wherein the non-embryonic stem, non-germ cells are human cells.
 91. The method of claim 89, wherein the non-embryonic stem, non-embryonic germ, non-germ cells are derived from bone marrow.
 92. The method of claim 90, wherein the non-embryonic stem, non-embryonic germ, non-germ cells are derived from bone marrow.
 93. The method of claim 85, wherein cells are aggregated by the hanging drop method or forced aggregation method.
 94. The method of claim 85, wherein the aggregation of the aggregate is carried out in cell culture.
 95. The method of claim 85, wherein the aggregate contains about 10 cells to about 50,000 cells or more.
 96. The method of claim 85, wherein the aggregate contains about 1000 cells to about 5000 cells.
 97. The method of claim 85 or 86 further comprising admixing the disaggregated cells with a pharmaceutically-acceptable vehicle for administration to a subject. 